Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| * 243: | \[{21^{243}-1\over20}\] | 109 × 163 × 463 × 487 × 4779433 × 85775383 × 7429452749713<13> × 251097226443098886970664441840231990201201851332912023687544574398706423<72> × [32508489134371602947325452006986922075320265036137764382502216988213895323005737784954552102688141878939256568259641975725630438915767245472318133084604624899450811325447765194097430787950460872285665833373668249<212>] |