Divisor 21457

To determine if any number is divisible by 21457, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 43 and 499 - then it is divisible by 21457.

The following tests must pass:

• Test if a number is divisible by 43
• Test if a number is divisible by 499

Easy!