Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 219: | \[{21^{219}-1\over20}\] | 463 × 30661 × 49057 × 4072503517807<13> × 518345871043554451<18> × 188003670692248749667531096507<30> × 61696858341802393209061956517494037213<38> × 19898693551147310168930403737455235935457864432837633271728063037547573060993374242776699<89> × 5424905842809814580790135175148153005273370039115139875248165723989059011789226683837426053<91> |