PerfectNumber.java

/***************
 * A perfect number is a positive integer equal to the sum of its divisors, 
 * excluding itself. For instance, 28 is a perfect number because 1 + 2 + 4 + 7 + 14 = 28.
 ***************/
 
import java.util.*;
class PerfectNumber{
    public static void main(String[] args){

        Scanner input = new Scanner(System.in);

        System.out.print("Enter a number to check either It is perfect or not : ");
        int number = input.nextInt();

        int sum = 0;    
        int i=1;    
        while(i<number){
            if(number % i == 0){
                sum += i;
            }
            i++;
        }

        if(sum == number){
            System.out.println(number+" is a perfect number!");
        }else{
            System.out.println(number+" is NOT a perfect number!");
        }
    }
}