Divisor 20913

To determine if any number is divisible by 20913, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 3 and 6971 - then it is divisible by 20913.

The following tests must pass:

• Test if a number is divisible by 3
• The "Bart Zonneveld Test" for Divisibility by 6971

Easy!