Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 187: | \[{21^{187}-1\over20}\] | 51239 × 17513875027111<14> × 765464515091513689<18> × 1502097124754084594737<22> × 975445747250107665555691903049<30> × 893653232599703974920871369442322429783560168273312923073800591562358852946149890611480777927863456119289243404490761977035905704889551283604368072835558008119<159> |