Divisor 15977

To determine if any number is divisible by 15977, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 13 and 1229 - then it is divisible by 15977.

The following tests must pass:

• Test if a number is divisible by 13
• The "Yanik-Pascal Förster Test" for Divisibility by 1229

Easy!