45 (number)
From Wikipedia, the free encyclopedia
45 (forty-five) is the natural number following 44 and followed by 46.
| Cardinal | 45 forty-five |
| Ordinal | 45th forty-fifth |
| Factorization |  |
| Divisors | 1, 3, 5, 9, 15, 45 |
| Roman numeral | XLV |
| Binary | 101101 |
| Hexadecimal | 2D |
Contents |
[edit] In mathematics
Forty-five is a triangular number, a hexagonal and 16-gonal number, a Kaprekar number, and a Harshad number.
45 is the sixth positive integer with a prime factorization of the form p2q, with p and q being prime.
33 is the aliquot sum of 45 and the aliquot sequence of 45 is (45,33,15,9,4,3,1,0).
Since the greatest prime factor of 452 + 1 = 2026 is 1013, which is clearly more than 45 twice, 45 is a Størmer number.
[edit] In science
- The atomic number of rhodium
[edit] Astronomy
- Messier object M45, a magnitude 1.4 open cluster in the constellation Taurus, also known as the Pleiades
- The New General Catalogue object NGC 45, a magnitude 10.6 spiral galaxy in the constellation Cetus
- The Saros number of the solar eclipse series which began on -1436 March 30 and ended on -156 May 7. The duration of Saros series 45 was 1280.1 years, and it contained 72 solar eclipses.
- The Saros number of the lunar eclipse series which began on -1369 August 19 and ended on 182 March 8. The duration of Saros series 45 was 1550.6 years, and it contained 87 lunar eclipses.
[edit] In music
- A type of gramophone record classified by its revolution speed of 45 revolutions per minute (rpm)
- Included in the title of "45 and Fat", a 1996 song by Babybird
- The title of a 2002 song by Elvis Costello, "45", both referring to the 45 rpm singles and to the artist's age when he wrote the song, which was released when he was 47
- The title of a 2003 song by Shinedown, "45" see 45 (song)
- The title of a 2006 song by noodles, "45"
- The title of a 2007 song by Ryan Shaw, "Do the 45"
- The title of a 2007 song by The Saturday Knights, "45"
- The title of a 1982 album by Kino
- Repeated continuously in the 1997 song Brimful of Asha by Cornershop
[edit] In other fields
Forty-five may also refer to:
- In years of marriage, the sapphire wedding anniversary.
- A card game: Forty-five
- I-45 is the designation for a US interstate highway in Texas
- The '45 refers to the 1745 Jacobite Rising in Great Britain
- 45 (book), a book of essays by record producer Bill Drummond, derived both from the speed of a pop single and from his age when he finished writing it
- Guns or ammunition of .45 Caliber
- .45 (film), a 2006 motion picture.
- +45 is the telephony dialling code for Denmark
