Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 130: | \[{21^{130}-1\over20}\] | 2 × 5 × 11 × 79 × 131 × 521 × 40841 × 185641 × 189437 × 443431 × 516094151 × 7021471715414521<16> × 101619538800983513441<21> × 57931461377789233256346069736652710022521<41> × 47999819885150422820855221255204479443163906801765079421<56> |