Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 206: | \[{21^{206}-1\over20}\] | 2 × 11 × 4327 × 7211 × 49853 × 573079972724225525536065884172119<33> × 124182167703174868733039024056091426756491656943<48> × 1367397284535016101800205204505932360525244596116383<52> × 3578319942163234761948197423711625937273928656180280573469957211934243130134304207939291415435034091514822796033427258153670673<127> |