Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 246: | \[{21^{246}-1\over20}\] | 2 × 11 × 83 × 421 × 463 × 1231 × 1766117 × 14122861 × 83218931 × 17222085343<11> × 914531249431<12> × 52899783148909<14> × 342306022057032544447<21> × 1474011104949958983856849<25> × 367541000424902470501250402608394113<36> × 380770063539669474313312691529545132713<39> × 33985282117517881270903492784746835442538163<44> × 10534031885860928959842755452634273061203152273<47> × 48152932015379839157406236741567598261163445191<47> |