Perfect number in java:

A number whose sum of factors (excluding the number itself) is equal to the number is called a perfect number. In other words, if the sum of positive divisors (excluding the number itself) of a number equals the number itself is called a perfect number.

Example program:

public class Perfect_number
	{

		public static void main(String[] args)
		{
			int num=28;
	        int div=1;
	        int total = 0;
	        while(div<num)
	        {
	        	if(num%div==0)
	        	{
	        		System.out.println(div);
	        		total = total+div;
	        	}
	        	div++;
	        	
	        }
	        System.out.println(total);
			if(num==total)
			{
				System.out.println("Perfect");
			}

		}

	}

output: