Divisor 21691

To determine if any number is divisible by 21691, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 109 and 199 - then it is divisible by 21691.

The following tests must pass:

• Test if a number is divisible by 109
• Test if a number is divisible by 199

Easy!