Compare 20 vs 21
| Property | 20 | 21 |
|---|---|---|
| Type | composite number | semiprime |
| Unique factors | 2 | 2 |
| Total factors | 3 | 2 |
| Prime factorization | 22 × 51 | 31 × 71 |
| Prime factorization | 2 × 2 × 5 | 3 × 7 |
| Divisors count | 6 | 4 |
| Divisors | 1, 2, 4, 5, 10, 20 | 1, 3, 7, 21 |
| Number of properties | 0 | 1 |
| Semiprimes | 7th | |
| Roman numberals | XX | XXI |
| Base 2 | 101002 | 101012 |
| Base 3 | 2023 | 2103 |
| Base 4 | 1104 | 1114 |
| Base 5 | 405 | 415 |
| Base 6 | 326 | 336 |
| Base 7 | 267 | 307 |
| Base 8 | 248 | 258 |
| Base 9 | 229 | 239 |
| Base 10 | 2010 | 2110 |
| Base 11 | 1911 | 1a11 |
| Base 12 | 1812 | 1912 |
| Base 13 | 1713 | 1813 |
| Base 14 | 1614 | 1714 |
| Base 15 | 1515 | 1615 |
| Base 16 | 1416 | 1516 |