37 38 39
Cardinalthirty-eight
Ordinal38th
(thirty-eighth)
Factorization2 × 19
Divisors1, 2, 19, 38
Greek numeralΛΗ´
Roman numeralXXXVIII
Binary1001102
Ternary11023
Senary1026
Octal468
Duodecimal3212
Hexadecimal2616

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

Astronomy

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:

See also

References

  1. Sloane, N. J. A. (ed.). "Sequence A001358". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. 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.
  3. (sequence A005277 in the OEIS)
  4. Higgins, Peter (2008). Number Story: From Counting to Cryptography. New York: Copernicus. p. 53. ISBN 978-1-84800-000-1.
  5. 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.
  6. Fluck, Daniel (23 March 2010). "Color Blindness Tests". Colblinder. Retrieved 30 November 2022.
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