Check wheather a number is Perfect number or not.

Perfect number are summation of divisors of a number exclude the number ownself.

Eample 6,28.

Lets check 28. From 1 to 27 we need to check which number can divide 28.
then sum of all those number whose are divisors of 28.

28 = 1,2,7,14(divisors).

Now make sum of all divisors
1+2+7+14 = 28

so 28 is perfect number.

Again 6 divisors are 1,2,3

so, 1+2+3 = 6 which is also perfect number.

C program:

#include <stdio.h>

int main()
{

int number,perfect_number,start=1,sum=0;

printf("Input Any  Number: \n");
scanf("%d",&number);

while(start<number)
{
    if(number%start ==  0)

        sum= sum+start;
        start ++;
}
if(sum ==number)
{
    printf("%d is perfect number\n",number);
}
else
{
   printf("%d is not perfect number\n",number);
}

return 0;
}