Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 149: | \[{21^{149}-1\over20}\] | 1193 × 4149000929822858713<19> × 19200704422015926819331744380572154435059819<44> × 53919242439762773005242386860200557456243874686294562852445931950590020366014258150390180061554764542320310512176525567625295129239<131> |