Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| * 215: | \[{21^{215}-1\over20}\] | 5 × 13331 × 40841 × 32108273175191<14> × 222756144763231<15> × 35842614220783025524408588074144786493150233831596714503<56> × [13562599955176353510116932638420458071565457554655268437338931646916920143663769327768863717647580420852895912822766242059684418900050381749616225265431658758039362408990835103490754726347731<191>] |