Divisor 16729

To determine if any number is divisible by 16729, apply the "Jetpack Test":

1. If your number ("X") has 6 digits or more, separate the last (smallest) 5 digits from the rest. This makes two smaller numbers, call them L^eft and R^ight (note: don't add in trailing zeros to L). If there are fewer than 6 digits, L = 0 and therefore R = X.
2. Multiply L by 374 and subtract this from R.
3. Take that result and cross off its final digit (units). Take this new number and add 1673 times the digit you just crossed off. Call this final result "Y".
4. Y will be much smaller than X, but we have preserved divisibility by 16729. That is, your original number is divisible by 16729 if (and only if) Y is. Now that it's much smaller, with basic knowledge of your 16729-times tables, it should be easy to visually see if Y is divisible by 16729. If the Y is still much larger than 16729, the above process can be repeated until it does reduce to within small multiples of 16729.

Easy!