Base 20 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 86: | \[{20^{86}-1\over19}\] | 3 × 7 × 947 × 369122321 × 12541974245083294274833711773684280721275134101<47> × 4423036668279780761301352642429727962990898576959823<52> |