Fifty-four (54) is the natural number following 53 and preceding 55.

In mathematics

54 is a 19-gonal number and a Harshad number.

In science

• The atomic number of xenon

In astronomy,

Messier object M54, a magnitude 8.5 globular cluster in the constellation Sagittarius

The New General Catalogue object NGC 54 , a spiral galaxy in the constellation Cetus

The Saros number of the solar eclipse series which began on -1284 July 25 and ended on 32 September 3. The duration of Saros series 54 was 1316.2 years, and it contained 74 solar eclipses.

The Saros number of the lunar eclipse series which began on -964 May 14 and ended on 334 July 3. The duration of Saros series 54 was 1298.1 years, and it contained 73 lunar eclipses.

In other fields

Fifty-four is also:

• The code for international direct dial phone calls to Argentina.
• The title of a 1998 movie about Studio 54 starring Salma Hayek and Ryan Phillippe.
• The number of colored squares on a Rubik's cube.
• In the title of a 1960s television show titled Car 54, Where Are You?.
• The code for the French Département of Meurthe-et-Moselle.

As a year, it can refer to AD 54, 54 BC, or 1954.