Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
86: | \[{21^{86}-1\over20}\] | 2 × 11 × 173 × 15739 × 126851 × 169367548429<12> × 1163308526467<13> × 478811691676843729951<21> × 35842614220783025524408588074144786493150233831596714503<56> |