Determine whether a given number is a Hyperperfect Number

Given a number, determine whether it is a valid Hyperperfect Number.
A number n is called k-hyperperfect if: n = 1 + k ∑_id_i where all d_i are the proper divisors of n.
Taking k = 1 will give us perfect numbers.

The first few k-hyperperfect numbers are 6, 21, 28, 301, 325, 496, 697, … with the corresponding values of k being 1, 2, 1, 6, 3, 1, 12, …

Examples:

Input :  N = 36, K = 1
Output :  34 is not 1-HyperPerfect
Explanation: 
The Divisors of 36 are 2, 3, 4, 6, 9, 12, 18
the sum of the divisors is 54. 
For N = 36 to be 1-Hyperperfect, it would 
require 36 = 1 + 1(54), which we see, is
invalid
 
Input :  N = 325, K = 3
Output :  325 is 3-HyperPerfect
Explanation: 
We can use the first condition to evaluate this 
as K is odd and > 1 so here p = (3*k+1)/2 = 5, 
q = (3*k+4) = 13 p and q are both prime, so we 
compute p^2 * q = 5 ^ 2 * 13 = 325
Hence N is a valid HyperPerfect number

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

// C++ 4.3.2 program to check whether a 
// given number is  k-hyperperfect 
#include <bits/stdc++.h> 
using namespace std; 
  
// function to find the sum of all 
// proper divisors (excluding 1 and N) 
int divisorSum(int N, int K) 
{ 
    int sum = 0; 
  
    // Iterate only until sqrt N as we are 
    // going to generate pairs to produce 
    // divisors 
    for (int i = 2 ; i <= ceil(sqrt(N)) ; i++) 
  
        // As divisors occur in pairs, we can 
        // take the values i and N/i as long 
        // as i divides N 
        if (N % i == 0) 
            sum += ( i + N/i ); 
  
    return sum; 
} 
  
// Function to check whether the given number 
// is prime 
bool isPrime(int n) 
{ 
    //base and corner cases 
    if (n == 1 || n == 0) 
        return false; 
  
    if (n <= 3) 
        return true; 
  
    // Since integers can be represented as 
    // some 6*k + y where y >= 0, we can eliminate 
    // all integers that can be expressed in this 
    // form 
    if (n % 2 == 0 || n % 3 == 0) 
        return false; 
  
    // start from 5 as this is the next prime number 
    for (int i=5; i*i<=n; i=i+6) 
        if (n % i == 0 || n % ( i + 2 ) == 0) 
            return false; 
  
    return true; 
} 
  
// Returns true if N is a K-Hyperperfect number 
// Else returns false. 
bool isHyperPerfect(int N, int K) 
{ 
    int sum = divisorSum(N, K); 
  
    // Condition from the definition of hyperperfect 
    if ((1 + K * (sum)) == N) 
        return true; 
    else
        return false; 
} 
  
// Driver function to test for hyperperfect numbers 
int main() 
{ 
    int N1 = 1570153, K1 = 12; 
    int N2 = 321, K2 = 3; 
  
    // First two statements test against the condition 
    // N = 1 + K*(sum(proper divisors)) 
    if (isHyperPerfect(N1, K1)) 
        cout << N1 << " is " << K1  
             <<"-HyperPerfect" << "\n"; 
    else
        cout << N1 << " is not " << K1  
             <<"-HyperPerfect" << "\n"; 
  
    if (isHyperPerfect(N2, K2)) 
        cout << N2 << " is " << K2  
             <<"-HyperPerfect" << "\n"; 
    else
        cout << N2 << " is not " << K2  
             <<"-HyperPerfect" << "\n"; 
  
    return 0; 
} 

Java

// Java program to check  
// whether a given number 
// is k-hyperperfect 
import java.io.*; 
  
class GFG  
{ 
      
// function to find the  
// sum of all proper  
// divisors (excluding  
// 1 and N) 
static int divisorSum(int N,  
                      int K) 
{ 
    int sum = 0; 
  
    // Iterate only until  
    // sqrt N as we are  
    // going to generate  
    // pairs to produce 
    // divisors 
    for (int i = 2 ; 
             i <= Math.ceil(Math.sqrt(N));  
             i++) 
  
        // As divisors occur in  
        // pairs, we can take  
        // the values i and N/i  
        // as long as i divides N 
        if (N % i == 0) 
            sum += (i + N / i); 
  
    return sum; 
} 
  
// Function to check  
// whether the given 
// number is prime 
static boolean isPrime(int n) 
{ 
    // base and corner cases 
    if (n == 1 || n == 0) 
        return false; 
  
    if (n <= 3) 
        return true; 
  
    // Since integers can be  
    // represented as some  
    // 6*k + y where y >= 0,  
    // we can eliminate all  
    // integers that can be  
    // expressed in this form 
    if (n % 2 == 0 ||  
        n % 3 == 0) 
        return false; 
  
    // start from 5 as this  
    // is the next prime number 
    for (int i = 5;  
             i * i <= n; i = i + 6) 
        if (n % i == 0 ||  
            n % ( i + 2 ) == 0) 
            return false; 
  
    return true; 
} 
  
// Returns true if N is  
// a K-Hyperperfect number 
// Else returns false. 
static boolean isHyperPerfect(int N, 
                              int K) 
{ 
    int sum = divisorSum(N, K); 
  
    // Condition from the  
    // definition of hyperperfect 
    if ((1 + K * (sum)) == N) 
        return true; 
    else
        return false; 
} 
  
// Driver Code 
public static void main (String[] args) 
{ 
    int N1 = 1570153, K1 = 12; 
    int N2 = 321, K2 = 3; 
      
    // First two statements test  
    // against the condition  
    // N = 1 + K*(sum(proper divisors)) 
    if (isHyperPerfect(N1, K1)) 
        System.out.println (N1 + " is " + K1 +  
                            "-HyperPerfect" ); 
    else
        System.out.println(N1 + " is not " + K1 +  
                               "-HyperPerfect" ); 
      
    if (isHyperPerfect(N2, K2)) 
        System.out.println( N2 + " is " + K2 +  
                            "-HyperPerfect" ); 
    else
        System.out.println(N2 + " is not " + K2 +  
                                "-HyperPerfect"); 
} 
} 
  
// This code is contributed by ajit 

C#

// C# program to check  
// whether a given number 
// is k-hyperperfect 
using System; 
  
class GFG 
{ 
      
// function to find the  
// sum of all proper  
// divisors (excluding  
// 1 and N) 
static int divisorSum(int N,  
                      int K) 
{ 
    int sum = 0; 
  
    // Iterate only until  
    // sqrt N as we are  
    // going to generate  
    // pairs to produce 
    // divisors 
    for (int i = 2 ; 
             i <= Math.Ceiling(Math.Sqrt(N));  
             i++) 
  
        // As divisors occur in  
        // pairs, we can take  
        // the values i and N/i  
        // as long as i divides N 
        if (N % i == 0) 
            sum += (i + N / i); 
  
    return sum; 
} 
  
// Function to check  
// whether the given 
// number is prime 
static bool isPrime(int n) 
{ 
    // base and corner cases 
    if (n == 1 || n == 0) 
        return false; 
  
    if (n <= 3) 
        return true; 
  
    // Since integers can be  
    // represented as some  
    // 6*k + y where y >= 0,  
    // we can eliminate all  
    // integers that can be  
    // expressed in this form 
    if (n % 2 == 0 ||  
        n % 3 == 0) 
        return false; 
  
    // start from 5 as this  
    // is the next prime number 
    for (int i = 5;  
            i * i <= n; i = i + 6) 
        if (n % i == 0 ||  
            n % ( i + 2 ) == 0) 
            return false; 
  
    return true; 
} 
  
// Returns true if N is  
// a K-Hyperperfect number 
// Else returns false. 
static bool isHyperPerfect(int N, 
                           int K) 
{ 
    int sum = divisorSum(N, K); 
  
    // Condition from the  
    // definition of hyperperfect 
    if ((1 + K * (sum)) == N) 
        return true; 
    else
        return false; 
} 
  
// Driver Code 
static public void Main () 
{ 
  
int N1 = 1570153, K1 = 12; 
int N2 = 321, K2 = 3; 
  
// First two statements  
// test against the   
// condition N = 1 + K* 
// (sum(proper divisors)) 
if (isHyperPerfect(N1, K1)) 
    Console.WriteLine(N1 + " is " + K1 +  
                      "-HyperPerfect" ); 
else
    Console.WriteLine(N1 + " is not " + K1 +  
                          "-HyperPerfect" ); 
  
if (isHyperPerfect(N2, K2)) 
    Console.WriteLine( N2 + " is " + K2 +  
                       "-HyperPerfect" ); 
else
    Console.WriteLine(N2 + " is not " + K2 +  
                           "-HyperPerfect"); 
} 
} 
  
// This code is contributed 
// by akt_mit 

PHP

<?php 
// PHP 4.3.2 program to check  
// whether a given number is  
// k-hyperperfect 
  
// function to find the sum  
// of all proper divisors  
// (excluding 1 and N) 
function divisorSum($N, $K) 
{ 
    $sum = 0; 
  
    // Iterate only until  
    // sqrt N as we are 
    // going to generate  
    // pairs to produce 
    // divisors 
    for ($i = 2 ; 
         $i <= ceil(sqrt($N)) ; $i++) 
  
        // As divisors occur in 
        // pairs, we can take the 
        // values i and N/i as long 
        // as i divides N 
        if ($N % $i == 0) 
            $sum += ( $i + $N / $i); 
  
    return $sum; 
} 
  
// Function to check whether  
// the given number is prime 
function isPrime($n) 
{ 
    // base and corner cases 
    if ($n == 1 || $n == 0) 
        return false; 
  
    if ($n <= 3) 
        return true; 
  
    // Since integers can be  
    // represented as some 6*k + y  
    // where y >= 0, we can  
    // eliminate all integers that  
    // can be expressed in this form 
    if ($n % 2 == 0 || $n % 3 == 0) 
        return false; 
  
    // start from 5 as this 
    // is the next prime number 
    for ($i = 5;  
         $i * $i <= $n; $i = $i + 6) 
        if ($n % $i == 0 ||  
            $n % ($i + 2) == 0) 
            return false; 
  
    return true; 
} 
  
// Returns true if N is a  
// K-Hyperperfect number 
// Else returns false. 
function isHyperPerfect($N, $K) 
{ 
    $sum = divisorSum($N, $K); 
  
    // Condition from the  
    // definition of hyperperfect 
    if ((1 + $K * ($sum)) == $N) 
        return true; 
    else
        return false; 
} 
  
// Driver Code 
$N1 = 1570153; 
$K1 = 12; 
$N2 = 321; 
$K2 = 3; 
  
// First two statements test  
// against the condition  
// N = 1 + K*(sum(proper divisors)) 
if (isHyperPerfect($N1, $K1)) 
    echo $N1 , " is " , $K1,  
           "-HyperPerfect" , "\n"; 
else
    echo $N1 , " is not " , $K1,  
         "-HyperPerfect" , "\n"; 
  
if (isHyperPerfect($N2, $K2)) 
    echo $N2 , " is " , K2,  
          "-HyperPerfect" , "\n"; 
else
    echo $N2 , " is not " , $K2 , 
          "-HyperPerfect" , "\n"; 
  
// This code is contributed 
// by akt_mit 
?> 

Output:

1570153 is 12-HyperPerfect
321 is not 3-HyperPerfect

Given k, we can perform a few checks in special cases to determine whether the number is hyperperfect:

If K > 1 and K is odd , then let p = (3*k+1)/2 and q = 3*k+4 . If p and q are prime, then p²q is k-hyperperfect
If p and q are distinct odd primes such that K(p + q ) = pq – 1 for some positive integral value of K, then pq is k-hyperperfect

Reference :
https://en.wikipedia.org/wiki/Hyperperfect_number

This article is contributed by Deepak Srivatsav. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

C#

PHP

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