Compare 391 vs 397
| Property | 391 | 397 |
|---|---|---|
| Type | semiprime | prime |
| Unique factors | 2 | 1 |
| Total factors | 2 | 1 |
| Prime factorization | 171 × 231 | 3971 |
| Prime factorization | 17 × 23 | 397 |
| Divisors count | 4 | 2 |
| Divisors | 1, 17, 23, 391 | 1, 397 |
| Number of properties | 1 | 8 |
| Additive primes | 45th | |
| Cousin primes (1st member) | 22nd | |
| Cuban primes 1 | 8th | |
| Happy primes | 21st | |
| Isolated primes | 37th | |
| Left-truncatable primes | 31st | |
| Primes | 78th | |
| Pythagorean primes | 37th | |
| Semiprimes | 122nd | |
| Roman numberals | CCCXCI | CCCXCVII |
| Base 2 | 1100001112 | 1100011012 |
| Base 3 | 1121113 | 1122013 |
| Base 4 | 120134 | 120314 |
| Base 5 | 30315 | 30425 |
| Base 6 | 14516 | 15016 |
| Base 7 | 10667 | 11057 |
| Base 8 | 6078 | 6158 |
| Base 9 | 4749 | 4819 |
| Base 10 | 39110 | 39710 |
| Base 11 | 32611 | 33111 |
| Base 12 | 28712 | 29112 |
| Base 13 | 24113 | 24713 |
| Base 14 | 1dd14 | 20514 |
| Base 15 | 1b115 | 1b715 |
| Base 16 | 18716 | 18d16 |