Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
65: | \[{21^{65}-1\over20}\] | 5 × 79 × 131 × 40841 × 189437 × 443431 × 516094151 × 47999819885150422820855221255204479443163906801765079421<56> |