Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 250: | \[{21^{250}-1\over20}\] | 2 × 53 × 11 × 101 × 251 × 21001 × 40841 × 185641 × 2031851 × 11093851 × 183175229895001<15> × 248303068144516751<18> × 27385718497004633851<20> × 61856751975900984009042515310001<32> × 52149276366245640092567568918361137482401249751<47> × 174507638556458782829201078129997701559651097610731092944095622192833751<72> × 1022489037962669248379370596767610133652264632743914995422849949035287375154623906974122897251<94> |