Divisor 16991

To determine if any number is divisible by 16991, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 13 and 1307 - then it is divisible by 16991.

The following tests must pass:

• Test if a number is divisible by 13
• The "Matthew Nanney Test" for Divisibility by 1307

Easy!