Harshad Number Calculator

This Harshad number calculator tells you whether any whole number you enter is a Harshad number, also known as a Niven number, meaning it divides evenly into the sum of its own digits. Harshad numbers matter in number theory and recreational maths because they sit at a simple but surprisingly rich intersection of a number's value and the way its digits are written, and testing for them is a common exercise in programming and divisibility practice. You enter a whole number, and the calculator works out the digit sum by adding each digit together, then checks whether the original number divides evenly by that digit sum. The result card tells you plainly whether the number is or is not a Harshad number, and shows the digit sum and, when the test passes, the quotient of the number divided by its digit sum. Every single digit number is automatically a Harshad number, since any number divides itself, but as numbers grow the property becomes less predictable, which is part of what makes them interesting to explore. Try entering numbers like 18, 21 or 100 to see the pattern for yourself, or test a number you already suspect is special. The name comes from the Sanskrit for joy giver, coined by the mathematician D. R. Kaprekar, and the same numbers are also called Niven numbers after Ivan Niven.

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