Compare 991 vs 998
| Property | 991 | 998 |
|---|---|---|
| Type | prime | semiprime |
| Unique factors | 1 | 2 |
| Total factors | 1 | 2 |
| Prime factorization | 9911 | 21 × 4991 |
| Prime factorization | 991 | 2 × 499 |
| Divisors count | 2 | 4 |
| Divisors | 1, 991 | 1, 2, 499, 998 |
| Number of properties | 10 | 1 |
| Additive primes | 89th | |
| Chen primes | 115th | |
| Emirps | 36th | |
| Isolated primes | 98th | |
| Lucky primes | 42nd | |
| Primes | 167th | |
| Semiprimes | 299th | |
| Sexy primes (1st member) | 74th | |
| Solinas primes | 43rd | |
| Super primes | 39th | |
| Ulam primes | 18th | |
| Roman numberals | CMXCI | CMXCVIII |
| Base 2 | 11110111112 | 11111001102 |
| Base 3 | 11002013 | 11002223 |
| Base 4 | 331334 | 332124 |
| Base 5 | 124315 | 124435 |
| Base 6 | 43316 | 43426 |
| Base 7 | 26147 | 26247 |
| Base 8 | 17378 | 17468 |
| Base 9 | 13219 | 13289 |
| Base 10 | 99110 | 99810 |
| Base 11 | 82111 | 82811 |
| Base 12 | 6a712 | 6b212 |
| Base 13 | 5b313 | 5ba13 |
| Base 14 | 50b14 | 51414 |
| Base 15 | 46115 | 46815 |
| Base 16 | 3df16 | 3e616 |