Write a C Program to find perfect number.

Definition of perfect number or what is perfect number? 

Perfect number is a positive number which sum of all positive divisors excluding that number is equal to that number. For example 6 is perfect number since divisor of 6 are 1, 2 and 3.  Sum of its divisor is

1 + 2+ 3 =6

Note: 6 is the smallest perfect number.

Next perfect number is 28 since 1+ 2 + 4 + 7 + 14 = 28

Some more perfect numbers: 496, 8128

#include<stdio.h>

int main(){

  int n,i=1,sum=0;

  printf("Enter a number: ");

  scanf("%d",&n);

  while(i<n)

  {

      if(n%i==0) 

           sum=sum+i;

          i++;

  }

  if(sum==n)

      printf("%d is a perfect number",n);

  else

      printf("%d is not a perfect number",n);

  return 0;

}

Sample output:

Enter a number: 6

6 is a perfect number