Compare 661 vs 809
| Property | 661 | 809 |
|---|---|---|
| Type | prime | prime |
| Unique factors | 1 | 1 |
| Total factors | 1 | 1 |
| Prime factorization | 6611 | 8091 |
| Prime factorization | 661 | 809 |
| Divisors count | 2 | 2 |
| Divisors | 1, 661 | 1, 809 |
| Number of properties | 5 | 7 |
| Additive primes | 65th | 74th |
| Centered decagonal primes | 8th | |
| Chen primes | 95th | |
| Good primes | 39th | |
| Primes | 121st | 140th |
| Pythagorean primes | 57th | 68th |
| Sophie germain primes | 35th | |
| Twin primes (1st member) | 31st | |
| Twin primes (2nd member) | 30th | |
| Roman numberals | DCLXI | DCCCIX |
| Base 2 | 10100101012 | 11001010012 |
| Base 3 | 2201113 | 10022223 |
| Base 4 | 221114 | 302214 |
| Base 5 | 101215 | 112145 |
| Base 6 | 30216 | 34256 |
| Base 7 | 16337 | 22347 |
| Base 8 | 12258 | 14518 |
| Base 9 | 8149 | 10889 |
| Base 10 | 66110 | 80910 |
| Base 11 | 55111 | 67611 |
| Base 12 | 47112 | 57512 |
| Base 13 | 3bb13 | 4a313 |
| Base 14 | 35314 | 41b14 |
| Base 15 | 2e115 | 38e15 |
| Base 16 | 29516 | 32916 |