Divisor 20409

To determine if any number is divisible by 20409, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 3 and 6803 - then it is divisible by 20409.

The following tests must pass:

• Test if a number is divisible by 3
• The "Lennard van der Putten Test" for Divisibility by 6803

Easy!