19 (number)
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| 19 | 10 | 9 |
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19 (nineteen) is the natural number following 18 and preceding 20. It is a prime number.
| Cardinal | 19 nineteen |
| Ordinal | 19th nineteenth |
| Factorization | prime |
| Divisors | 1, 19 |
| Roman numeral | XIX |
| Roman numeral (Unicode) | XIX, xix |
| Binary | 10011 |
| Octal | 23 |
| Duodecimal | 17 |
| Hexadecimal | 13 |
Contents |
[edit] In mathematics
Nineteen is the 8th smallest prime number. The sequence continues 23, 29, 31, 37... 19 is the seventh Mersenne prime exponent. 19 is the smallest Higgs prime for squares and cubes that has an index among Higgs primes that is less than its index among primes overall (because 17 is not a Higgs prime).
Every positive integer is the sum of at most nineteen fourth powers (see Waring's problem).
Nineteen is a centered triangular number, centered hexagonal number, and an octahedral number.
Nineteen is a Heegner number.
19 is the fourth alternating factorial, as it is equal to −(1!) + 2! + −(3!) + 4!
With respect to divisibility, nineteen has a very simple test: 19 divides 100a + b if and only if it divides a + 4b.
In base 10, it is a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 1, 9, 10, 19... The decimal expansion of 1/19 has a period of maximum length: 18 digits. Regardless of the base, 19 is a strictly non-palindromic number. In Roman numerals, however, 19 is the largest palindromic prime.
[edit] In science
- The atomic number of potassium.
[edit] Astronomy
- Messier object M19, a magnitude 8.5 globular cluster in the constellation Ophiuchus
- The New General Catalogue object NGC 19, a barred spiral galaxy in the constellation Andromeda
- The number of years of the Metonic cycle
- The Saros number of the solar eclipse series which began on 2333 BC June 15 and ended on 1035 BC August 1. The duration of Saros series 19 was 1298.1 years, and it contained 73 solar eclipses.
- The Saros number of the lunar eclipse series which began on 2031 BC March 24 and ended on 731 BC May 11. The duration of Saros series 19 was 1298.1 years, and it contained 73 lunar eclipses.
[edit] In religion
- The number of years in each cycle of the intercalated Hebrew calendar, in which 7 of the 19 years are leap years
- The number of angels guarding Hell according to the Qur'an: "Over it is nineteen" (74:30)
- The number of surat Maryam in the Qur'an
- The number of letters in the Bismillah formula "In the name of God, Most Gracious, Most Merciful" in Arabic [1]
- A number encoded in the Qur'an [2] as claimed by Dr. Rashad Khalifa, a biochemist from the USA, about the Qur'an [3]
- The Bahá'í calendar is structured such that a year contains 19 months of 19 days each, as well as a 19-year cycle and a 361-year (19x19) supercycle. The Báb and his disciples formed a group of 19, and there were 19 Apostles of Bahá'u'lláh.
[edit] In music
"19" is a 1985 hit song by Paul Hardcastle, with a strong anti-war message, based on scratched soundbites taken from a documentary about the Vietnam War in which 19 is claimed to have been the average age of United States soldiers killed in the conflict (a fact which is widely disputed). The song was parodied by British satirist Rory Bremner as N-n-nineteen, Not Out, the title referring to the English cricket team's risible performance against the West Indies in the previous year.
With a similar name and anti-Vietnam War theme, I Was Only 19 (A Walk in the Light Green), by the Australian group Redgum reached number one on the Australian charts in 1983. In 2005 a hip hop version of the song (called I was only Nineteen) was produced by The Herd, and was voted in at #18 in the 2005 Triple J Hottest 100 playlist.
Other songs with the number 19 in their titles:
- "Nineteen" by Buck-O-Nine
- "Nineteen" by Phil Lynott
- "Nineteen" by the Old 97's
- "Hey, Nineteen" by Steely Dan
- "19th Nervous Breakdown" by the Rolling Stones
- "Nineteen Forever" by Joe Jackson
- "I Got A Feeling (Just Nineteen)" by Eagles of Death Metal
Nineteen has been used as an alternative to twelve for a division of the octave into equal parts. This idea goes back to Salinas in the sixteenth century, and is interesting in part because it gives a system of meantone tuning, being close to 1/3 comma meantone.
19 is also the title of Evan Yo's first album, because Evan was nineteen years old when the album was released.
[edit] In other fields
Nineteen is
- The nineteenth state to enter the Union was Indiana
- Part of the name of a breakfast cereal: Product 19
- The Soviet submarine K-19 was the first Soviet nuclear ballistic submarine
- I-19 is the designation for a US interstate highway in Arizona
- 19 years is very close to 235 lunations. See Metonic cycle
- A significant recurring number (which comes to denote a sense of unreality and foreboding) in the Dark Tower novels by author Stephen King
- In golf the "19th hole" is the clubhouse bar. In miniature golf it is an extra hole on which the winner earns an instant prize
- A number encoded in Chemistry as claimed by Dr. Peter Plichta, a German chemist [4]. Also see [5] for Plichta's claimed code-19 in chemistry
- The retired football jersey number of Hall of Famers Johnny Unitas and Lance Alworth
- The retired baseball jersey number of Baseball Hall of Fame members Robin Yount and Tony Gwynn.
- The retired basketball jersey number of Willis Reed.
- The retired hockey jersey number of Steve Yzerman.
- The number of Colorado Avalanche center and captain Joe Sakic
- 19 x 19 is also the standard size of a Go Board
- It is not possible to earn a score of 19 in a single hand of cribbage
- June 19th is the birthday of Garfield, the comic strip created by Jim Davis. See[6].
- Juneteenth refers to June 19, 1865, the final surrender of the last forces of the Confederate States of America and the formal end of slavery anywhere in the USA.
- the number of brothers Nick and Steve Thiede.
- Nineteen plays a symbolic role in Stephen King's fiction.
[edit] Historical years
A.D. 19, 19 B.C., 1919, 2019, etc.
