Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 407: | \[2^{407}-1\] | 23 × 89 × 223 × 3257 × 616318177 × 3068001817 × 1826375940722234754636475033<28> × 64374964789425759023795123420605218308370931223311543823123770088423<68> |