Divisor 7991

To determine if any number is divisible by 7991, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 61 and 131 - then it is divisible by 7991.

The following tests must pass:

• Test if a number is divisible by 61
• Test if a number is divisible by 131

Easy!