Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
131: | \[{21^{131}-1\over20}\] | 1049 × 2470162463 × 229027002385831089465739609724278489582787<42> × 13687052074332591601541282383301905745371122445745433886164039445273884190933317364799124290237834799701349135257178899<119> |