72 (number)
72 is the natural number following 71 and preceding 73.
| |||
| Cardinal | seventy-two | ||
| Ordinal | 72nd (seventy-second) | ||
| Factorization | 
| ||
| Divisors | 2, 3, 4, 6, 8, 9, 12, 18, 24, 36 | ||
| Roman numeral | LXXII | ||
| Binary | 1001000 | ||
| Hexadecimal | 48 | ||
In mathematics
Seventy-two is the sum of four consecutive primes (13 + 17 + 19 + 23), as well as the sum of six consecutive primes (5 + 7 + 11 + 13 + 17 + 19). 72 is a Harshad number and a pronic number.
In normal space, the exterior angles of an equilateral pentagon measure 72 degrees each.
There are 17 solutions to the equation φ(x) = 72, more than any integer below 72, making it a highly totient number.
In science
- The atomic number of hafnium
In astronomy,
- Messier object M72, a magnitude 10.0 globular cluster in the constellation Aquarius
- The New General Catalogue object NGC 72, a magnitude 13.5 barred spiral galaxy in the constellation Andromeda
- The Saros number of the solar eclipse series which began on -727 August 16 and ended on 752 January 21. The duration of Saros series 72 was 1478.1 years, and it contained 83 solar eclipses.
- The Saros number of the lunar eclipse series which began on -407 June 5 and ended on 891 July 25. The duration of Saros series 72 was 1298.1 years, and it contained 73 lunar eclipses.
In other fields
Seventy-two is also:
- The conventional number of scholars translating the Septuagint, according to the legendary account in the "[Pseudo-Aristeas|Letter of Aristeas]]".
- The conventional number of disciples sent forth by Jesus in Luke 10 in some mss (seventy in others).
- The number of hours in three days.
- The total number of books in the Holy Bible in the Catholic version if the Book of Lamentations is considered part of the Book of Jeremiah.
- In dpi, the standard resolution of an Apple Macintosh screen.
- The number of the French department Sarthe.
- The designation of USA Interstate 72, a freeway that runs from Missouri to Illinois.
- The registry of the U.S. Navy's nuclear aircraft carrier USS Abraham Lincoln (CVN-72), named after U.S. President Abraham Lincoln.
- The designation of the Soviet T-72 tank.
- In the movie The Red Violin, the lot number of the Bussotti red violin at the DuVal auction house.
- The year AD 72, 72 BC, or 1972.