Divisor 21501

To determine if any number is divisible by 21501, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 9 and 2389 - then it is divisible by 21501.

The following tests must pass:

• Test if a number is divisible by 9
• The "Adam Flenar Test" for Divisibility by 2389

Easy!