Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 661: | \[2^{661}-1\] | 1330270433 × 3370159489168519<16> × 1009157848082361225065617<25> × 118420287267066844820208926433723871<36> × 17858769391813189478549404315577297646468853412925918136831275019859096428810527270736800933577430978666397275839559<116> |