Compare 651 vs 661
| Property | 651 | 661 |
|---|---|---|
| Type | composite number | prime |
| Unique factors | 3 | 1 |
| Total factors | 3 | 1 |
| Prime factorization | 31 × 71 × 311 | 6611 |
| Prime factorization | 3 × 7 × 31 | 661 |
| Divisors count | 8 | 2 |
| Divisors | 1, 3, 7, 21, 31, 93, 217, 651 | 1, 661 |
| Number of properties | 0 | 5 |
| Additive primes | 65th | |
| Centered decagonal primes | 8th | |
| Primes | 121st | |
| Pythagorean primes | 57th | |
| Twin primes (2nd member) | 30th | |
| Roman numberals | DCLI | DCLXI |
| Base 2 | 10100010112 | 10100101012 |
| Base 3 | 2200103 | 2201113 |
| Base 4 | 220234 | 221114 |
| Base 5 | 101015 | 101215 |
| Base 6 | 30036 | 30216 |
| Base 7 | 16207 | 16337 |
| Base 8 | 12138 | 12258 |
| Base 9 | 8039 | 8149 |
| Base 10 | 65110 | 66110 |
| Base 11 | 54211 | 55111 |
| Base 12 | 46312 | 47112 |
| Base 13 | 3b113 | 3bb13 |
| Base 14 | 34714 | 35314 |
| Base 15 | 2d615 | 2e115 |
| Base 16 | 28b16 | 29516 |