Compare 991 vs 1021
| Property | 991 | 1021 |
|---|---|---|
| Type | prime | prime |
| Unique factors | 1 | 1 |
| Total factors | 1 | 1 |
| Prime factorization | 9911 | 10211 |
| Prime factorization | 991 | 1021 |
| Divisors count | 2 | 2 |
| Divisors | 1, 991 | 1, 1021 |
| Number of properties | 10 | 8 |
| Additive primes | 89th | |
| Chen primes | 115th | |
| Emirps | 36th | 38th |
| Harmonic primes | 61st | |
| Isolated primes | 98th | |
| Long primes | 62nd | |
| Lucky primes | 42nd | 45th |
| Primes | 167th | 172nd |
| Pythagorean primes | 83rd | |
| Sexy primes (1st member) | 74th | |
| Solinas primes | 43rd | 46th |
| Super primes | 39th | |
| Twin primes (2nd member) | 36th | |
| Ulam primes | 18th | |
| Roman numberals | CMXCI | MXXI |
| Base 2 | 11110111112 | 11111111012 |
| Base 3 | 11002013 | 11012113 |
| Base 4 | 331334 | 333314 |
| Base 5 | 124315 | 130415 |
| Base 6 | 43316 | 44216 |
| Base 7 | 26147 | 26567 |
| Base 8 | 17378 | 17758 |
| Base 9 | 13219 | 13549 |
| Base 10 | 99110 | 102110 |
| Base 11 | 82111 | 84911 |
| Base 12 | 6a712 | 71112 |
| Base 13 | 5b313 | 60713 |
| Base 14 | 50b14 | 52d14 |
| Base 15 | 46115 | 48115 |
| Base 16 | 3df16 | 3fd16 |