For the year A.D. 59, see 59.
Fifty-nine (59, LIX) is the natural number following fifty-eight and preceding sixty.
Fifty-nine is the 17th smallest prime number. The next is sixty-one, with which it comprises a twin prime.
Fifty-nine is also:
- The atomic number of praseodymium, a lanthanide.
- The number of icosahedra discussed in H. S. M. Coxeter, P. Du Val, H. T. Flather, and J. F. Petrie's book The Fifty-Nine Icosahedra.
- The designation of Interstate 59, a freeway that runs from Louisiana to Georgia.