Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 140: | \[{21^{140}-1\over20}\] | 22 × 5 × 11 × 13 × 17 × 29 × 41 × 43 × 71 × 631 × 1471 × 3319 × 3697 × 40841 × 50261 × 140351 × 185641 × 4149601 × 4325861 × 20028751 × 78555121 × 81867661 × 920421641 × 68454248717<11> × 92152520881<11> × 421503321597121<15> × 72413241922093801<17> × 146453218893643838406593856001717939447081<42> |