Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 408: | \[{21^{408}-1\over20}\] | 23 × 11 × 13 × 172 × 61 × 73 × 103 × 137 × 409 × 421 × 463 × 953 × 3181 × 11969 × 38047 × 97241 × 2610929 × 300293033 × 518118697 × 2691707418840001<16> × 114089969144083169<18> × 729040918680274021<18> × 5357156372335908409<19> × 1502097124754084594737<22> × 1556912582127465166281841<25> × 399981195234791390040813065378761<33> × 51233569124705721849500009982296618143<38> × 538235381016666585866626514626393657321<39> × 852043808963865734150481907266273656921<39> × 20813096623337757798888685318376525907607<41> × 3698302276780585510340644054997690968312381<43> × 79684969036050448196226812869339200527816905918793018868569512057350099256903089083591086160290514347304390545620270123138414529<128> |