Sixty-three (63, LXIII) is a natural number following sixty-two and preceding sixty-four. It is a composite number with the divisors being 3, 7, 9 and 21. Its factorization is:

Sixty-three is also:

  • The atomic number of europium, a lanthanide.
  • The code for international direct dial calls to the Philippines.
  • The registry of the U.S. Navy's aircraft carrier USS Kitty Hawk (CV-63).

This article is about the number 63. For the year AD 63, see 63.