Java Program to Find The Perfect Number

In this article, we will understand how to check whether a number is perfect number or not. Perfect number is a positive integer that is equal to the sum of its factors other than itself.

Below is a demonstration of the same −

Input

Suppose our input is −

Enter the number : 496

Output

The desired output would be −

The number 496 is a perfect number

Algorithm

Step 1 - START
Step 2 - Declare two long values namely my_input, my_sum and an integer value 'i'.
Step 3 - Read the required values from the user/ define the values
Step 4 - Using a while condition, iterate until it reaches the specified condition.
Step 5 - Check of the value 'my_input % i' leaves no reminder. If yes, add ‘my_sum’ to 'i' and assign it to 'my_sum'. Increment 'i' value.
Step 6 - If the 'my_sum' value is equal to the input, it's a perfect number, else it's not a perfect number
Step 7 - Display the result
Step 8 - Stop

Example 1

Here, the input is being entered by the user based on a prompt. You can try this example live in our coding ground tool .

import java.util.Scanner;
public class PerfectNumber{
   public static void main(String args[]){
      long my_input, my_sum;
      int i;
      my_sum=0;
      System.out.println("Required packages have been imported");
      Scanner my_scanner = new Scanner(System.in);
      System.out.println("A reader object has been defined ");
      System.out.print("Enter the number : ");
      my_input = my_scanner.nextLong();
      i=1;
      while(i <= my_input/2){
         if(my_input % i == 0){ 
            my_sum = my_sum + i;
         }
         i++;
      }
      if(my_sum==my_input)
         System.out.println("The number " +my_input+" is a perfect number");
      else
         System.out.println("The number " +my_input+" is not a perfect number");
   }
}

Output

Required packages have been imported
A reader object has been defined
Enter the number : 496
The number 496 is a perfect number

Example 2

Here, the integer has been previously defined, and its value is accessed and displayed on the console.

import java.util.Scanner;
public class PerfectNumber{
   public static void main(String args[]){
      long my_input, my_sum;
      int i;
      my_sum=0;
      my_input = 496;
      System.out.println("The number is defined as " +my_input);
      i=1;
      while(i <= my_input/2){
         if(my_input % i == 0){ 
            my_sum = my_sum + i;
         }
         i++;
      }
      if(my_sum==my_input)
         System.out.println("The number " +my_input+" is a perfect number");
      else
        System.out.println("The number " +my_input+" is not a perfect number");
   }
}

Output

The number is defined as 496
The number 496 is a perfect number