Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 88: | \[{21^{88}-1\over20}\] | 23 × 112 × 13 × 17 × 23 × 89 × 353 × 661 × 6073 × 97241 × 10362529 × 313433209 × 715521049 × 17513875027111<14> × 29831330140869137<17> × 32775913825604401<17> × 4718573764413203147069<22> |