Base 2 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
671: | \[2^{671}-1\] | 23 × 89 × 116356769 × 33491655209<11> × 64110547427930873<17> × 2305843009213693951<19> × 13646560594525825890627182668772241639702837721889959372317451952089<68> × 608833519146176962786346063898868909094632504100539398786357475514441579020823<78> |