Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
70: | \[{21^{70}-1\over20}\] | 2 × 5 × 11 × 43 × 71 × 631 × 1471 × 3319 × 40841 × 140351 × 185641 × 4149601 × 20028751 × 78555121 × 81867661 × 421503321597121<15> × 72413241922093801<17> |