Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 93: | \[{21^{93}-1\over20}\] | 373 × 463 × 1303 × 4540713283<10> × 3936833990413<13> × 272581865551637989<18> × 5490236844314625181981860471139<31> × 7687249112242592598176964045333142849438561<43> |