Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 237: | \[{21^{237}-1\over20}\] | 463 × 2687 × 10903 × 18013 × 1834380224794697528813671<25> × 15208288358346544216626697<26> × 59186552621710498906371968419372921<35> × 122435283552586211204658864416622901<36> × 261513239159154440967606433092726647<36> × 89901952358431562958449798748325858761462984321471389412647949825389266543378859544416726999726364894599046601366398092735664885351196793065267<143> |