Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 170: | \[{21^{170}-1\over20}\] | 2 × 5 × 11 × 1361 × 1531 × 11969 × 40841 × 185641 × 3549804001 × 39748187549971<14> × 114089969144083169<18> × 1502097124754084594737<22> × 11500287881306297400572689205013166485061<41> × 346846213951614446714019035689488886491130381<45> × 14923927201647231692066520884112168808387109788676424881<56> |