Compare 661 vs 670
| Property | 661 | 670 |
|---|---|---|
| Type | prime | composite number |
| Unique factors | 1 | 3 |
| Total factors | 1 | 3 |
| Prime factorization | 6611 | 21 × 51 × 671 |
| Prime factorization | 661 | 2 × 5 × 67 |
| Divisors count | 2 | 8 |
| Divisors | 1, 661 | 1, 2, 5, 10, 67, 134, 335, 670 |
| Number of properties | 5 | 0 |
| Additive primes | 65th | |
| Centered decagonal primes | 8th | |
| Primes | 121st | |
| Pythagorean primes | 57th | |
| Twin primes (2nd member) | 30th | |
| Roman numberals | DCLXI | DCLXX |
| Base 2 | 10100101012 | 10100111102 |
| Base 3 | 2201113 | 2202113 |
| Base 4 | 221114 | 221324 |
| Base 5 | 101215 | 101405 |
| Base 6 | 30216 | 30346 |
| Base 7 | 16337 | 16457 |
| Base 8 | 12258 | 12368 |
| Base 9 | 8149 | 8249 |
| Base 10 | 66110 | 67010 |
| Base 11 | 55111 | 55a11 |
| Base 12 | 47112 | 47a12 |
| Base 13 | 3bb13 | 3c713 |
| Base 14 | 35314 | 35c14 |
| Base 15 | 2e115 | 2ea15 |
| Base 16 | 29516 | 29e16 |