Divisor 19781

To determine if any number is divisible by 19781, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 131 and 151 - then it is divisible by 19781.

The following tests must pass:

• Test if a number is divisible by 131
• Test if a number is divisible by 151

Easy!