# Check if a number with even number of digits is palindrome or not

Given a number **N** containing an **even number of digits**. The task is to check whether that number is palindrome or not.

**Examples:**

Input:N = 123321Output:PalindromeInput:1234Output:Not palindrome

A **Naive Approach **is to traverse from the front and back of that number and stop where they do not match.

An **Efficient Approach** is to use the below fact:

Palindrome Number having

even numberofdigitsis always divisible by 11.

Suppose the number is **d1 d2 d3 d4…dn**, where**d1, d2, d3..** are **digits** of a number. If it is a palindrome then d1 = dn, d2 = dn-1, d3 = dn-2…..and so on. Now since **divisibility of 11** states that the **difference of sum of alternate digits of a number** should be **zero** and same in the case of palindrome having even no. of digits i.e.

d1 + d3 + …+ dn-1 = d2 + d4 + d6 + … + dn

So, a **palindromic number** having **even number** of **digits** is always **divisible by 11.**

## C++

`// C++ program to find number is palindrome` `// or not without using any extra space` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to check if the number is palindrome` `bool` `isPalindrome(` `int` `n)` `{` ` ` `// if divisible by 11 then true` ` ` `if` `(n % 11 == 0) {` ` ` `return` `true` `;` ` ` `}` ` ` `// if not divisible by 11` ` ` `return` `false` `;` `}` `// Driver code` `int` `main()` `{` ` ` `isPalindrome(123321) ? cout << ` `"Palindrome"` ` ` `: cout << ` `"Not Palindrome"` `;` ` ` `return` `0;` `}` |

## Java

`// Java program to find number` `// is palindrome or not without` `// using any extra space` `class` `GFG` `{` ` ` `// Function to check if the` ` ` `// number is palindrome` ` ` `static` `boolean` `isPalindrome(` `int` `n)` ` ` `{` ` ` `// if divisible by 11 then true` ` ` `if` `(n % ` `11` `== ` `0` `)` ` ` `{` ` ` `return` `true` `;` ` ` `}` ` ` ` ` `// if not divisible by 11` ` ` `return` `false` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{` ` ` `System.out.println(isPalindrome(` `123321` `) ?` ` ` `"Palindrome"` `:` ` ` `"Not Palindrome"` `);` ` ` `}` `}` `// This code is contributed by Bilal` |

## Python3

`# Python 3 program to find number is palindrome` `# or not without using any extra space.` `# Function to check if the number is palindrome` `def` `isPalindrome(n) :` ` ` `# if divisible by 11 then return True` ` ` `if` `n ` `%` `11` `=` `=` `0` `:` ` ` `return` `True` ` ` `# if not divisible by 11 then return False` ` ` `return` `False` `# Driver code` `if` `__name__ ` `=` `=` `"__main__"` `:` ` ` `n ` `=` `123321` ` ` ` ` `if` `isPalindrome(n) :` ` ` `print` `(` `"Palindrome"` `)` ` ` `else` `:` ` ` `print` `(` `"Not Palindrome"` `)` ` ` `# This code is contributed by ANKITRAI1` |

## C#

`// C# program to find number` `// is palindrome or not without` `// using any extra space` `using` `System;` `class` `GFG` `{` ` ` `// Function to check if the` ` ` `// number is palindrome` ` ` `static` `bool` `isPalindrome(` `int` `n)` ` ` `{` ` ` `// if divisible by` ` ` `// 11 then true` ` ` `if` `(n % 11 == 0)` ` ` `{` ` ` `return` `true` `;` ` ` `}` ` ` ` ` `// if not divisible by 11` ` ` `return` `false` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `Console.Write(isPalindrome(123321) ?` ` ` `"Palindrome"` `:` ` ` `"Not Palindrome"` `);` ` ` `}` `}` `// This code is contributed` `// by ChitraNayal` |

## PHP

`<?php` `// PHP program to find number` `// is palindrome or not without` `// using any extra space` `// Function to check if the` `// number is palindrome` `function` `isPalindrome(` `$n` `)` `{` ` ` `// if divisible by` ` ` `// 11 then true` ` ` `if` `(` `$n` `% 11 == 0)` ` ` `{` ` ` `return` `true;` ` ` `}` ` ` `// if not divisible by 11` ` ` `return` `false;` `}` `// Driver code` `echo` `isPalindrome(123321) ?` ` ` `"Palindrome"` `:` ` ` `"Not Palindrome"` `;` `// This code is contributed` `// by ChitraNayal` `?>` |

## Javascript

`<script>` `// Javascript program to find number` `// is palindrome or not without` `// using any extra space` ` ` `// Function to check if the` ` ` `// number is palindrome` ` ` `function` `isPalindrome(n)` ` ` `{` ` ` `// if divisible by 11 then true` ` ` `if` `(n % 11 == 0)` ` ` `{` ` ` `return` `true` `;` ` ` `}` ` ` ` ` `// if not divisible by 11` ` ` `return` `false` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `document.write(isPalindrome(123321) ?` ` ` `"Palindrome"` `:` ` ` `"Not Palindrome"` `);` `// This code contributed by Princi Singh` `</script>` |

**Output**

Palindrome

**Time Complexity:** O(1)**Auxiliary Space: **O(1)