/*
A perfect number is a positive integer that is equal to the sum
of its proper positive divisors, that is, the sum of its positive
divisors excluding the number itself. Equivalently, a perfect number
is a number that is half the sum of all of its positive divisors.
The first perfect number is 6, because 1, 2 and 3 are its proper
positive divisors, and 1 + 2 + 3 = 6. Equivalently, the number 6
is equal to half the sum of all its positive divisors:
		( 1 + 2 + 3 + 6 ) / 2 = 6.
*/

public class IsPerfectNumber
{

    public boolean isPerfectNumber(int number)
    {
        int temp = 0;
        for(int i=1; i<=number/2; i++)
            {
                if(number%i == 0)
                    {
                        temp += i;
                    }
            }
        if(temp == number)
            {
                System.out.println("It is a perfect number");
                return true;
            }
        else
            {
                System.out.println("It is not a perfect number");
                return false;
            }
    }

    public static void main(String a[])
    {
        IsPerfectNumber ipn = new IsPerfectNumber();
        System.out.println("Is perfect number: "+ipn.isPerfectNumber(28));
    }
}