Sixty-five (65, LXV) is a natural number following sixty-four and preceding sixty-six. It is a triangular number, and a Cullen number as well as a composite number with the divisors being 5 and 13. Its factorization is:
Sixty-five is also:
- The atomic number of terbium, a lanthanide.
- A common speed limit, in miles per hour, for freeways in many U.S. states.
- The designation of Interstate 65, a freeway that runs from Alabama to Indiana.
- The code for international direct dial phone calls to Singapore.
- The standard age for retirement in the UK, Germany and other countries.
- The registry of the U.S. Navy's nuclear aircraft carrier USS Enterprise (CVN-65).