71 (number)
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71 is the natural number following 70 and preceding 72.
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| Cardinal | seventy-one | ||
| Ordinal | 71st (seventy-first) | ||
| Factorization | <math>''prime''<math> | ||
| Roman numeral | LXXI | ||
| Binary | 1000111 | ||
| Hexadecimal | 47 | ||
In mathematics
It is the 20th prime number. The next is seventy-three, with which it composes a twin prime. It is also a permutable prime with seventeen. If we add up the primes less than 71 (2 through 67), we get 568, which is divisible by 71, 8 times. 71 is the largest supersingular prime. Also, 712 = 7! + 1, making it part of the last known pair of Brown numbers, as (71, 7).
71 is a centered heptagonal number.
In science
- The atomic number of lutetium, a lanthanide
In astronomy,
- Messier object M71, a magnitude 8.5 globular cluster in the constellation Sagitta
- The New General Catalogue object (http://www.ngcic.org/) NGC 71, a magnitude 13.2 peculiar spiral galaxy in the constellation Andromeda
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -702 October 8 and ended on 777March 14. The duration of Saros series 71 was 1478.4 years, and it contained 83 solar eclipses.
- The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -472 June 4 and ended on 808 July 11. The duration of Saros series 71 was 1280.1 years, and it contained 72 lunar eclipses.
In other fields
Seventy-one is also:
- The designation of USA Interstate 71, which runs from Kentucky to Ohio.
- The registry of the U.S. Navy's nuclear aircraft carrier USS Theodore Roosevelt (CVN-71), named after U.S. President Theodore Roosevelt.
- The number of the French department Saône-et-Loire.
- The year AD 71, 71 BC, or 1971.
- A sexual position similar to 69, but with two fingers in the anus.
eo:Sepdek unu ko:71 ia:71 it:Settantuno ja:71 sl:71 (število) sv:71 (tal) zh:71