Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 108: | \[{21^{108}-1\over20}\] | 22 × 11 × 13 × 17 × 19 × 37 × 61 × 109 × 163 × 199 × 421 × 463 × 613 × 1693 × 3181 × 5077 × 17497 × 4779433 × 85775383 × 4344847859197<13> × 7429452749713<13> × 7101932659132249<16> × 360697466924286697<18> × 1103447100998503280657719551313<31> |