harshad number

A **Harshad number** is an integer that is divisible by the sum of its digits. Also known as a Niven number, it holds a special place in number theory due to its interesting divisibility properties. For example, 18 is a Harshad number because the sum of its digits (1 + 8 = 9) divides 18 evenly (18 ÷ 9 = 2). Harshad numbers appear in various mathematical contexts and puzzles, making them a fascinating topic for enthusiasts and educators alike.