Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 212: | \[{21^{212}-1\over20}\] | 22 × 11 × 13 × 17 × 107 × 1697 × 8693 × 14910160703858993<17> × 207612155793974069<18> × 372515213872960388437<21> × 4555268603071594349347155493<28> × 156211149550774441321811821193<30> × 167223466685805761701453712891<30> × 3494212075791575531835909274237181<34> × 138876454254937405984677776325817472562106222324957308697021557495271802915933293997452682809<93> |