Compare 1990 vs 1999
| Property | 1990 | 1999 |
|---|---|---|
| Type | composite number | prime |
| Unique factors | 3 | 1 |
| Total factors | 3 | 1 |
| Prime factorization | 21 × 51 × 1991 | 19991 |
| Prime factorization | 2 × 5 × 199 | 1999 |
| Divisors count | 8 | 2 |
| Divisors | 1, 2, 5, 10, 199, 398, 995, 1990 | 1, 1999 |
| Number of properties | 0 | 8 |
| Centered triangular primes | 10th | |
| Cousin primes (1st member) | 65th | |
| Primes | 303rd | |
| Prime triplets (2nd member) | 50th | |
| Prime triplets (3rd member) | 49th | |
| Sexy primes (2nd member) | 128th | |
| Sexy prime triplets (3rd member) | 50th | |
| Twin primes (2nd member) | 61st | |
| Roman numberals | MCMXC | MCMXCIX |
| Base 2 | 111110001102 | 111110011112 |
| Base 3 | 22012013 | 22020013 |
| Base 4 | 1330124 | 1330334 |
| Base 5 | 304305 | 304445 |
| Base 6 | 131146 | 131316 |
| Base 7 | 55427 | 55547 |
| Base 8 | 37068 | 37178 |
| Base 9 | 26519 | 26619 |
| Base 10 | 199010 | 199910 |
| Base 11 | 154a11 | 155811 |
| Base 12 | 119a12 | 11a712 |
| Base 13 | ba113 | baa13 |
| Base 14 | a2214 | a2b14 |
| Base 15 | 8ca15 | 8d415 |
| Base 16 | 7c616 | 7cf16 |