Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 53: | \[{21^{53}-1\over20}\] | 1697 × 207612155793974069<18> × 372515213872960388437<21> × 4555268603071594349347155493<28> |
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 53: | \[{21^{53}-1\over20}\] | 1697 × 207612155793974069<18> × 372515213872960388437<21> × 4555268603071594349347155493<28> |