138 (number)
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 |
| Contents |
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
- 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.