Divisor 21553

To determine if any number is divisible by 21553, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 7 and 3079 - then it is divisible by 21553.

The following tests must pass:

• Test if a number is divisible by 7
• The "Omri Galai Test" for Divisibility by 3079

Easy!