138 (number)

138 (one hundred [and] thirty-eight) is the natural number following 137 and preceding 139.

137 138 139
Cardinalone hundred thirty-eight
Ordinal138th
(one hundred thirty-eighth)
Factorization2 × 3 × 23
Divisors1, 2, 3, 6, 23, 46, 69, 138
Greek numeralΡΛΗ´
Roman numeralCXXXVIII
Binary100010102
Ternary120103
Senary3506
Octal2128
DuodecimalB612
Hexadecimal8A16

In mathematics

  • 138 is a sphenic number, the sum of four consecutive primes (29 + 31 + 37 + 41), and the smallest product of three primes, such that in base 10, the third prime is a concatenation of the other two: .
  • 138 is the third 47-gonal number[1] and an Ulam number,[2] as well as a one step palindrome (138 + 831 = 969.)
  • 138 is the 72nd normal congruent number[3] and the 49th primitive or square free congruent number.[4]
  • using two radii to divide a circle according to the golden ratio yields sectors of approximately 138° (the golden angle) and 222° in degree system.

In astronomy

In the military

In transportation

In media

In other fields

138 is also:

See also

References

  1. Sloane, N. J. A. (ed.). "Sequence A095311 (47-gonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
  2. A002858 in the OEIS
  3. in the OEIS
  4. in the OEIS
  5. McHeyzer-Williams LJ, Cool M, McHeyzer-Williams MG. Antigen- specific B cell memory: expression and replenishment of a novel B220- memory b cell compartment. J Exp Med. 2000;191:1149–1166.
  6. McHeyzer-Williams MG, McLean MJ, Lalor PA, Nossal GJV. Antigen- driven B cell differentiation in vivo. J Exp Med. 1993;178:295–307.
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