One hundred thirty-eight (138) is the natural number following one hundred thirty-seven and preceding one hundred thirty-nine.

Cardinal	One hundred [and] thirty-four
Ordinal	138th
Factorization
Divisors	2, 3, 6, 23, 46, 69
Roman numeral	CXXXVIII
Binary	10001010
Hexadecimal	8A

In mathematics

Its factorization makes 138 a sphenic number. This number is the sum of four consecutive primes (29 + 31 + 37 + 41). It is the smallest product of 3 primes such that in base 10 the third prime is a concatenation of the other two.

138 is the third 47-gonal number.

138 is an Ulam number (Sloane's A002858).

It is also the number of stellations of the Triakis Tetrahedron .

In science

In astronomy,

The New General Catalogue object NGC138 , a spiral galaxy in the constellation Pisces

Asteroid 138 Tolosa

The Saros number of the solar eclipse series which began on 1472 June 6 and will end on 2716 July 11 The duration of Saros series 138 is 1244.0 years, and it contains 70 solar eclipses.

The Saros number of the lunar eclipse series which began on 1503 October 5 and will end on 2982 March 30. The duration of Saros series 138 is 1442.4 years, and it contains 81 lunar eclipses.

In other fields

One hundred thirty-eight is also:

• The episode number of The Simpsons "138th Episode Spectacular". Most other shows would have used a round number.
• Occasionally used as a substitute for 1138 in George Lucas's oeuvre.
• The year AD 138 or 138 BC.

References

• http://mathworld.wolfram.com/TriakisTetrahedronStellations.html