Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 399: | \[2^{399}-1\] | 72 × 127 × 337 × 32377 × 73417 × 83791 × 524287 × 1212847 × 163537220852725398851434325720959<33> × 29724614739876344125010817433703775877960388838436140673<56> |