Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 221: | \[{21^{221}-1\over20}\] | 79 × 189437 × 516094151 × 8077975881587<13> × 1502097124754084594737<22> × 329870879538394852145879<24> × 26258430201102267069846036102373770869240984222585574648494619254267058300262510269018206138403970279078625719583692170248590988369887886079118741468647833915883351981054548740587279115158510329910843775291606775202877<218> |