Compare 81 vs 91
| Property | 81 | 91 |
|---|---|---|
| Type | composite number | semiprime |
| Unique factors | 1 | 2 |
| Total factors | 4 | 2 |
| Prime factorization | 34 | 71 × 131 |
| Prime factorization | 3 × 3 × 3 × 3 | 7 × 13 |
| Divisors count | 5 | 4 |
| Divisors | 1, 3, 9, 27, 81 | 1, 7, 13, 91 |
| Number of properties | 0 | 1 |
| Semiprimes | 31st | |
| Roman numberals | LXXXI | XCI |
| Base 2 | 10100012 | 10110112 |
| Base 3 | 100003 | 101013 |
| Base 4 | 11014 | 11234 |
| Base 5 | 3115 | 3315 |
| Base 6 | 2136 | 2316 |
| Base 7 | 1447 | 1607 |
| Base 8 | 1218 | 1338 |
| Base 9 | 1009 | 1119 |
| Base 10 | 8110 | 9110 |
| Base 11 | 7411 | 8311 |
| Base 12 | 6912 | 7712 |
| Base 13 | 6313 | 7013 |
| Base 14 | 5b14 | 6714 |
| Base 15 | 5615 | 6115 |
| Base 16 | 5116 | 5b16 |