C program to check whether the number is a Perfect number or not

#include <stdio.h>
int main()
{
    int i, number, sum = 0;

    /* Input a number from user */
    printf("Enter any number to check perfect number: ");
    scanf("%d", &number);

    /* Calculate sum of all proper divisors */
    /* Here number/2 for reduce this loop */
    for(i = 1; i <= number / 2; i++)
    {
        /* If i is a divisor of num */
        if(number%i == 0)
        {
            sum += i;
        }
    }

    /* Check whether the sum of proper divisors is equal to num */
    if(number == sum)
    {
        printf("%d is Perfect Number", number);
    }
    else
    {
        printf("%d is Not Perfect Number", number);
    }

    return 0;
}

Output

Enter any number to check perfect number: 6
6 is Perfect Number