| ||||
|---|---|---|---|---|
| Cardinal | thirty-eight | |||
| Ordinal | 38th (thirty-eighth)  | |||
| Factorization | 2 × 19 | |||
| Divisors | 1, 2, 19, 38 | |||
| Greek numeral | ΛΗ´ | |||
| Roman numeral | XXXVIII | |||
| Binary | 1001102 | |||
| Ternary | 11023 | |||
| Senary | 1026 | |||
| Octal | 468 | |||
| Duodecimal | 3212 | |||
| Hexadecimal | 2616 | |||
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. 34 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 523022617466601111760007224100074291199999999 which is the 16th factorial prime.[2]
 - There is no answer to the equation φ(x) = 38, making 38 a nontotient.[3]
 - 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.[4]
 
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

Ishihara test: Most people will see the number 38, but people with red-green color blindness might see 88 instead.
Thirty-eight is also:
- The 38th parallel north is the pre-Korean War boundary between North Korea and South Korea.[5]
 - 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.[6]
 - 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 Fallout: New Vegas.
 
See also
References
- ↑ Sloane, N. J. A. (ed.). "Sequence A001358". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
 - ↑ Sloane, N. J. A. (ed.). "Sequence A002982 (Numbers n such that n! - 1 is prime)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
 - ↑ (sequence A005277 in the OEIS)
 - ↑ Higgins, Peter (2008). Number Story: From Counting to Cryptography. New York: Copernicus. p. 53. ISBN 978-1-84800-000-1.
 - ↑ Fry, Michael (5 August 2013). "National Geographic, Korea, and the 38th Parallel". National Geographic. Archived from the original on February 25, 2021. Retrieved 15 May 2021.
 - ↑ Fluck, Daniel (23 March 2010). "Color Blindness Tests". Colblinder. Retrieved 30 November 2022.
 
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