Write a Program in Java to input a number and check whether it is a Harshad Number or Niven Number or not.

Harshad Number : In recreational mathematics, a Harshad number (or Niven number), is an integer (in base 10) that is divisible by the sum of its digits.

Let’s understand the concept of Harshad Number through the following example:

•    The number 18 is a Harshad number in base 10, because the sum of the digits 1 and 8 is 9 (1 + 8 = 9), and 18 is divisible by 9 (since 18 % 9 = 0)

The first few Harshad numbers in base 10 are:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42, 45, 48, 50, 54, 60, 63, 70, 72, 80, 81, 84, 90, 100, 102, 108, 110, 111, 112, 114, 117, 120, 126, 132, 133, 135, 140, 144, 150, 152, 153, 156, 162, 171, 180, 190, 192, 195, 198, 200 etc.

Program:
import java.util.*;
class HarshadNumber
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number : ");
        int n = sc.nextInt();
        int c = n, d, sum = 0;
        //finding sum of digits
        while(c>0)
        {
            d = c%10;
            sum = sum + d;
            c = c/10;
        }
        if(n%sum == 0)
            System.out.println(n+" is a Harshad Number.");
        else
            System.out.println(n+" is not a Harshad Number.");     
    }
}