Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 145: | \[{21^{145}-1\over20}\] | 5 × 59 × 40841 × 1504231 × 1103704099 × 246763300513<12> × 687613372491653<15> × 10560867746962116514771<23> × 21933305517206008074555499460677419485784113293205521<53> × 33516108735906048319408808055288256871397516473638732084022278909501<68> |