Divisor 21857

To determine if any number is divisible by 21857, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 11 and 1987 - then it is divisible by 21857.

The following tests must pass:

• Test if a number is divisible by 11
• The "Bankräubär Test" for Divisibility by 1987

Easy!