PerfectNumber.java

/*********************************************************************************************************************
 Perfect Number
 ==============
 What is the perfect number?
 A perfect number is a positive integer which is equal to the sum of its proper positive divisors.
 Proper positive divisors are positive integers that fully divide the perfect number without leaving a remainder and exclude the perfect number itself.
 For example, take the number 6:
 Its proper divisors are 1, 2, and 3 (since 6 is the value of the perfect number, it is excluded), and the sum of its proper divisors is 1 + 2 + 3 = 6.

 Therefore, 6 is a perfect number (as well as the first perfect number).


 Write a method named isPerfectNumber with one parameter of type int named number.

 If number is < 1, the method should return false.

 The method must calculate if the number is perfect. If the number is perfect, the method should return true; otherwise, it should return false.


 EXAMPLE INPUT/OUTPUT:

 isPerfectNumber(6); should return true since its proper divisors are 1, 2, 3 and the sum is 1 + 2 + 3 = 6

 isPerfectNumber(28); should return true since its proper divisors are 1, 2, 4, 7, 14 and the sum is 1 + 2 + 4 + 7 + 14 = 28

 isPerfectNumber(5); should return false since its only proper divisor is 1 and the sum is 1 not 5

 isPerfectNumber(-1); should return false since the number is < 1

 HINT: Use a while or for loop.

 HINT: Use the remainder operator.

 NOTE: The method isPerfectNumber ​should be defined as public static like we have been doing so far in the course.

 NOTE: Do not add a main method to the solution code.
 **********************************************************************************************************************/
public class PerfectNumber {
    public static boolean isPerfectNumber(int number)
    {
        if (number>=1)
        {
            int sum=0;
            for (int i=1;i<=number/2;i++)
            {
                if (number%i==0)
                    sum+=i;
            }
            return (sum==number);
        }
        else
            return false;
    }
}