Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 136: | \[{21^{136}-1\over20}\] | 23 × 11 × 13 × 172 × 137 × 953 × 11969 × 97241 × 2610929 × 300293033 × 2691707418840001<16> × 114089969144083169<18> × 5357156372335908409<19> × 1502097124754084594737<22> × 399981195234791390040813065378761<33> × 852043808963865734150481907266273656921<39> |