Eighty-nine (89, LXXXIX) is the natural number following eighty-eight and preceeding ninety.
- Hexadecimal: 59
- Binary: 01011001
- Factors: 1, 89.
- the 24th prime number, following eighty-three and preceeding ninety-seven, a Fibonacci number
- Ordinal number: eighty-ninth
- the atomic number of actinium (Ac)
- the model number of CBU-89 Gator, TI-89
- part of the name of the baseball team Oklahoma City 89ers (1962-1997)
- the number of the French department Yonne
- the designation of Interstate 89, a freeway that runs from New Hampshire to Vermont
- the year AD 89, 1889, or 1989.