37 (thirty-seven) is the natural number following 36 and preceding 38.

In mathematics

37 is the 12th prime number, and the 3rd isolated prime without a twin prime.^[1]

• 37 is the first irregular prime.^[2]
• The sum of the squares of the first 37 primes is divisible by 37.^[3]
• 37 is the median value for the second prime factor of an integer.^[4]
• Every positive integer is the sum of at most 37 fifth powers (see Waring's problem).^[5]
• It is the third cuban prime following 7 and 19.^[6]
• 37 is the fifth Padovan prime, after the first four prime numbers 2, 3, 5, and 7.^[7]
• It is also the fifth lucky prime, after 3, 7, 13, and 31.^[8]
• 37 is the third star number^[9] and the fourth centered hexagonal number.^[10]

There are exactly 37 complex reflection groups.

The smallest magic square, using only primes and 1, contains 37 as the value of its central cell:^[11]

Its magic constant is 37 x 3 = 111, where 3 and 37 are the first and third base-ten unique primes (the second such prime is 11).^[12]

In decimal 37 is a permutable prime with 73, which is the 21st prime number. By extension, the mirroring of their digits and prime indexes makes 73 the only Sheldon prime. In moonshine theory, whereas all p ⩾ 73 are non-supersingular primes, the smallest such prime is 37.

37 requires twenty-one steps to return to 1 in the 3x + 1 Collatz problem, as do adjacent numbers 36 and 38.^[13] The two closest numbers to cycle through the elementary {16, 8, 4, 2, 1} Collatz pathway are 5 and 32, whose sum is 37.^[14] The trajectories for 3 and 21 both require seven steps to reach 1.^[13]

The first two integers that return ${\displaystyle 0}$ for the Mertens function (2 and 39) have a difference of 37.^[15] Their product (2 × 39) is the twelfth triangular number 78. Their sum is 41, which is the constant term in Euler's lucky numbers that yield prime numbers of the form k² − k + 41; the largest of which (1601) is a difference of 78 from the second-largest prime (1523) generated by this quadratic polynomial.^[16]

In science

• The atomic number of rubidium
• The normal human body temperature in degrees Celsius

In other fields

House number in Baarle (in its Belgian part)

Thirty-seven is:

• The number of the French department Indre-et-Loire^[18]
• The number of slots in European roulette (numbered 0 to 36, the 00 is not used in European roulette as it is in American roulette)
• The RSA public exponent used by PuTTY
• Richard Nixon, 37th president of the United States.
• DEVO song "37" from "Hardcore Devo: Volume Two"

See also

• List of highways numbered 37
• Number Thirty-Seven, Pennsylvania, unincorporated community in Cambria County, Pennsylvania
• I37 (disambiguation)

References

External links

Wikimedia Commons has media related to 37 (number).

• 37 Heaven Large collection of facts and links about this number.