Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 63: | \[{20^{63}-1\over19}\] | 29 × 71 × 421 × 6679 × 32719 × 460951 × 64008001 × 8442733531<10> × 10287600958458182504983419994609358363826919<44> |