Compare 4 vs 19
| Property | 4 | 19 |
|---|---|---|
| Type | semiprime | prime |
| Unique factors | 1 | 1 |
| Total factors | 2 | 1 |
| Prime factorization | 22 | 191 |
| Prime factorization | 2 × 2 | 19 |
| Divisors count | 3 | 2 |
| Divisors | 1, 2, 4 | 1, 19 |
| Number of properties | 1 | 18 |
| Centered triangular primes | 1st | |
| Chen primes | 8th | |
| Cousin primes (1st member) | 4th | |
| Cuban primes 1 | 2nd | |
| Happy primes | 3rd | |
| Long primes | 3rd | |
| Pierpont primes | 7th | |
| Primes | 8th | |
| Prime quadruplets (4th member) | 2nd | |
| Prime quintuplet 1s (5th member) | 1st | |
| Prime quintuplet 2s (4th member) | 2nd | |
| Prime sextuplets (5th member) | 1st | |
| Prime triplets (2nd member) | 5th | |
| Prime triplets (3rd member) | 4th | |
| Semiprimes | 1st | |
| Sexy primes (2nd member) | 4th | |
| Sexy prime triplets (3rd member) | 2nd | |
| Solinas primes | 7th | |
| Twin primes (2nd member) | 4th | |
| Roman numberals | IV | XIX |
| Base 2 | 1002 | 100112 |
| Base 3 | 113 | 2013 |
| Base 4 | 104 | 1034 |
| Base 5 | 45 | 345 |
| Base 6 | 46 | 316 |
| Base 7 | 47 | 257 |
| Base 8 | 48 | 238 |
| Base 9 | 49 | 219 |
| Base 10 | 410 | 1910 |
| Base 11 | 411 | 1811 |
| Base 12 | 412 | 1712 |
| Base 13 | 413 | 1613 |
| Base 14 | 414 | 1514 |
| Base 15 | 415 | 1415 |
| Base 16 | 416 | 1316 |
