A number n is a Harshad (also called Niven) number if it is divisible by the sum of its digits. For example, 666 is divisible by 6 + 6 + 6, so it is a Harshad number.
Write a function to determine whether the given number is a Harshad number.
isHarshad(209) ➞ true
isHarshad(41) ➞ false
isHarshad(12255) ➞ true
N/A