Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 113: | \[{21^{113}-1\over20}\] | 227 × 332447 × 768053632358191<15> × 2848908845742998189988598903<28> × 13882020027413204621222579528393197501<38> × 5616674628667674074541197792169903784792943111117930947154929<61> |