Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 116: | \[{21^{116}-1\over20}\] | 22 × 11 × 13 × 17 × 59 × 349 × 1277 × 18097 × 1103704099 × 246763300513<12> × 687613372491653<15> × 1792484183066669<16> × 7865855595529911658005355038639053<34> × 9759093518513238012039627213817579718073176623974473<52> |