Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 153: | \[{21^{153}-1\over20}\] | 463 × 15607 × 38047 × 80031547 × 85775383 × 625770304116639832567<21> × 1502097124754084594737<22> × 34098331055594280023053<23> × 847586878961383719143557147<27> × 51233569124705721849500009982296618143<38> × 379395745875808971155324352649338339586035997<45> |