38 (number) explained

Number:	38
Divisor:	1, 2, 19, 38

38 (thirty-eight) is the natural number following 37 and preceding 39.

In mathematics

• specifically, the 11th discrete Semiprime,^[1] it being the 7th of the form (2.q).
• the first member of the third cluster of two discrete semiprimes 38, 39 the next such cluster is 57, 58.
• with an aliquot sum of 22 in an aliquot sequence of five composite numbers (38,22,14,10,8,7,1,0) to the Prime in the 7-aliquot tree. 38 is the first semiprime within a chain of 4 semiprimes in its aliquot sequence (38,22,14,10). The next semiprime with a four semiprime chain is 166.
• 38! − 1 yields which is the 16th factorial prime.^[2]
• There is no answer to the equation φ(x) = 38, making 38 a nontotient.
• 38 is the sum of the squares of the first three primes.
• 37 and 38 are the first pair of consecutive positive integers not divisible by any of their digits.
• 38 is the largest even number which cannot be written as the sum of two odd composite numbers.
• The sum of each row of the only non-trivial (order 3) magic hexagon is 38.^[3]

In science

• The atomic number of strontium

Astronomy

• The Messier object M38, a magnitude 7.0 open cluster in the constellation Auriga
• The New General Catalogue object NGC 38, a spiral galaxy in the constellation Pisces

In other fields

Thirty-eight is also:

• The 38th parallel north is the pre-Korean War boundary between North Korea and South Korea.^[4]
• The number of slots on an American roulette wheel (0, 00, and 1 through 36; European roulette does not use the 00 slot and has only 37 slots)
• The Ishihara test is a color vision test consisting of 38 pseudoisochromatic plates.^[5]
• A "38" is often the name for a snub nose .38 caliber revolver.
• The 38 class is the most famous class of steam locomotive used in New South Wales
• Gerald Ford, 38th President of the United States
• Arnold Schwarzenegger, 38th Governor of California, most recent Republican governor of California, and the second governor to be born outside of the United States
• Cats have a total of 38 chromosomes in their genome.
• Number used by Zane Smith and Front Row Motorsports to win the 2022 NASCAR Camping World Truck Series championship.
• The Lucky 38, the casino from .

See also

• List of highways numbered 38

Notes and References

1. A001358.
2. A002982. Numbers n such that n! - 1 is prime. 2016-05-31.
3. Book: Higgins, Peter . Number Story: From Counting to Cryptography . limited . 2008 . Copernicus . New York . 978-1-84800-000-1 . 53 .
4. Web site: Fry . Michael . National Geographic, Korea, and the 38th Parallel . https://web.archive.org/web/20210225074751/https://www.nationalgeographic.com/science/article/130805-korean-war-dmz-armistice-38-parallel-geography . dead . February 25, 2021 . National Geographic . 15 May 2021 . en . 5 August 2013.
5. Web site: Fluck. Daniel. Color Blindness Tests. Colblinder. 23 March 2010 . 30 November 2022.