Compare 21 vs 51
| Property | 21 | 51 |
|---|---|---|
| Type | semiprime | semiprime |
| Unique factors | 2 | 2 |
| Total factors | 2 | 2 |
| Prime factorization | 31 × 71 | 31 × 171 |
| Prime factorization | 3 × 7 | 3 × 17 |
| Divisors count | 4 | 4 |
| Divisors | 1, 3, 7, 21 | 1, 3, 17, 51 |
| Number of properties | 1 | 1 |
| Semiprimes | 7th | 18th |
| Roman numberals | XXI | LI |
| Base 2 | 101012 | 1100112 |
| Base 3 | 2103 | 12203 |
| Base 4 | 1114 | 3034 |
| Base 5 | 415 | 2015 |
| Base 6 | 336 | 1236 |
| Base 7 | 307 | 1027 |
| Base 8 | 258 | 638 |
| Base 9 | 239 | 569 |
| Base 10 | 2110 | 5110 |
| Base 11 | 1a11 | 4711 |
| Base 12 | 1912 | 4312 |
| Base 13 | 1813 | 3c13 |
| Base 14 | 1714 | 3914 |
| Base 15 | 1615 | 3615 |
| Base 16 | 1516 | 3316 |