Divisor 1891

To determine if any number is divisible by 1891, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 31 and 61 - then it is divisible by 1891.

The following tests must pass:

• Test if a number is divisible by 31
• Test if a number is divisible by 61

Easy!