For the year A.D. 49, see 49.

Forty-nine (44, XLIX) is the natural number following forty-eight and preceeding fifty. Its divisors are 1, 7, and 49; its factorisation is

It is a Somer pseudoprime based on 8.

Forty-nine is also:

  • The atomic number of indium.
  • The span between Jubilee years as ordained in the Holy Bible.
  • The number of strings on a harp and the number of keys on a celesta.
  • The code for international direct dial phone calls to Germany.
  • As in 49er, the moniker of those who participated in the 1849 gold rush.