Compare 21 vs 21
| Property | 21 | 21 |
|---|---|---|
| Type | semiprime | semiprime |
| Unique factors | 2 | 2 |
| Total factors | 2 | 2 |
| Prime factorization | 31 × 71 | 31 × 71 |
| Prime factorization | 3 × 7 | 3 × 7 |
| Divisors count | 4 | 4 |
| Divisors | 1, 3, 7, 21 | 1, 3, 7, 21 |
| Number of properties | 1 | 1 |
| Semiprimes | 7th | 7th |
| Roman numberals | XXI | XXI |
| Base 2 | 101012 | 101012 |
| Base 3 | 2103 | 2103 |
| Base 4 | 1114 | 1114 |
| Base 5 | 415 | 415 |
| Base 6 | 336 | 336 |
| Base 7 | 307 | 307 |
| Base 8 | 258 | 258 |
| Base 9 | 239 | 239 |
| Base 10 | 2110 | 2110 |
| Base 11 | 1a11 | 1a11 |
| Base 12 | 1912 | 1912 |
| Base 13 | 1813 | 1813 |
| Base 14 | 1714 | 1714 |
| Base 15 | 1615 | 1615 |
| Base 16 | 1516 | 1516 |