Divisor 19643

To determine if any number is divisible by 19643, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 13 and 1511 - then it is divisible by 19643.

The following tests must pass:

• Test if a number is divisible by 13
• The "Fearn Bishop Test" for Divisibility by 1511

Easy!