Divisor 19989

To determine if any number is divisible by 19989, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 9 and 2221 - then it is divisible by 19989.

The following tests must pass:

• Test if a number is divisible by 9
• The "Florian K Test" for Divisibility by 2221

Easy!