81 (number)
Eighty-one is a number. It comes between eighty and eighty-two, and is an odd number. It is also a square number.
| ||||
|---|---|---|---|---|
| Cardinal | eighty-one | |||
| Ordinal | 81st (eighty-first) | |||
| Factorization | 34 | |||
| Roman numeral | LXXXI | |||
| Binary | 10100012 | |||
| Ternary | 100003 | |||
| Quaternary | 11014 | |||
| Quinary | 3115 | |||
| Senary | 2136 | |||
| Octal | 1218 | |||
| Duodecimal | 6912 | |||
| Hexadecimal | 5116 | |||
| Vigesimal | 4120 | |||
| Base 36 | 2936 | |||