Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 107: | \[{21^{107}-1\over20}\] | 1734899 × 4272624310883<13> × 352523466309500183<18> × 55837009494804076861723<23> × 16339864316070753885738065827<29> × 62966131031683950925080167776709767184533584081571817<53> |