Divisor 8561

To determine if any number is divisible by 8561, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 7 and 1223 - then it is divisible by 8561.

The following tests must pass:

• Test if a number is divisible by 7
• The "Frans Test" for Divisibility by 1223

Easy!