37 is the natural number following 36 and preceding 38.

In mathematics

It is a prime number, the first irregular prime, a unique prime as well as a cuban prime of the form p = (x³ - y³) / (x - y),x = y + 1. It is a factor of all 3-digit base 10 repdigits, such as 111. It is a centered hexagonal number and a star number.

Every positive integer is the sum of at most 37 fifth powers (see Waring's problem).

In science

• The atomic number of rubidium.
• The normal human body temperature in degrees Celsius.
• In astronomy,
  • Messier object M37, a magnitude 6.0 open cluster in the constellation Auriga
  • The New General Catalogue object NGC 37 , a spiral galaxy in the constellation Phoenix
  • The Saros number of the solar eclipse series which began on -1794 June 25 and ended on -496 August 12. The duration of Saros series 37 was 1298.1 years, and it contained 73 solar eclipses.
  • The Saros number of the lunar eclipse series which began on -1492 April 3 and ended on -194 May 22. The duration of Saros series 37 was 1298.1 years, and it contained 73 lunar eclipses.

In other fields

Thirty-seven is:

• Part of the code for international direct dial phone calls to several smaller European countries.
• The number of the French department Indre-et-Loire.
• The number of slots in European Roulette.
• I-37 is the designation for a US interstate highway in Texas.
• The number used in a certain magic trick. In this trick the magician asks a person to think of a number that meets the following criteria: a. must be between 1 and 50, b. must have two digits, c. both digits must be odd, d. both digits cannot be the same. Only eight numbers meet these criteria: 13, 15, 17, 19, 31, 35, 37, and 39. Statistically, people will pick 37 over any of the other numbers. Therefore, the magician can use this probability to create the effect of mind-reading. Of course, it doesn't always work, but when it does, it provides for a very startling effect.
• The year A.D. 37, 37 BC, or 1937.