Base 21 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 161: | \[{21^{161}-1\over20}\] | 43 × 47 × 631 × 3319 × 19597 × 36709 × 4897051993<10> × 28514133943<11> × 32792468187424849<17> × 139870566115103282847737<24> × 989841672456580427804885218352119985137687<42> × 19527664822346443228748973869572070909123582858479071409999979815929801049293816407083453837<92> |