Divisor 21309

To determine if any number is divisible by 21309, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 3 and 7103 - then it is divisible by 21309.

The following tests must pass:

• Test if a number is divisible by 3
• The "Gheitz Test" for Divisibility by 7103

Easy!