Compare 661 vs 1531
| Property | 661 | 1531 |
|---|---|---|
| Type | prime | prime |
| Unique factors | 1 | 1 |
| Total factors | 1 | 1 |
| Prime factorization | 6611 | 15311 |
| Prime factorization | 661 | 1531 |
| Divisors count | 2 | 2 |
| Divisors | 1, 661 | 1, 1531 |
| Number of properties | 5 | 5 |
| Additive primes | 65th | |
| Centered decagonal primes | 8th | 13th |
| Isolated primes | 143rd | |
| Long primes | 91st | |
| Primes | 121st | 242nd |
| Pythagorean primes | 57th | |
| Twin primes (2nd member) | 30th | |
| Ulam primes | 22nd | |
| Roman numberals | DCLXI | MDXXXI |
| Base 2 | 10100101012 | 101111110112 |
| Base 3 | 2201113 | 20022013 |
| Base 4 | 221114 | 1133234 |
| Base 5 | 101215 | 221115 |
| Base 6 | 30216 | 110316 |
| Base 7 | 16337 | 43157 |
| Base 8 | 12258 | 27738 |
| Base 9 | 8149 | 20819 |
| Base 10 | 66110 | 153110 |
| Base 11 | 55111 | 117211 |
| Base 12 | 47112 | a7712 |
| Base 13 | 3bb13 | 90a13 |
| Base 14 | 35314 | 7b514 |
| Base 15 | 2e115 | 6c115 |
| Base 16 | 29516 | 5fb16 |