Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 81: | 421 × 64008001 × 150773239 × 879338701 × 298114935351301<15> × 7599707813206155097384225291<28> × 15721667458073376459082354447584949<35> |