Seventeen

The seventeen (17) is the natural number that follows 16 and precedes 18.

Math

• 7th prime number, after 13th and before 19.
• It is a permutable cousin with 71 (since when changing the position of the numbers you get another prime number).
• 17 is the third prime number of Fermat (n=2), after 5 and before 257. Thanks to this property you can build heptadecágonos with rule and step, as Carl Friedrich Gauss showed.
• Form a pair of twin prime numbers along with 19.
• It is a number of Leyland since 3² + 2³ = 17.
• 17 = 13 + 2+2 = 11+3+3 = 7+7+3
• Like (4+i)(4-i) = (1+4i)(1-4i)= 17, this number is not a cousin in the ring of the whole gaussians.
• Gauss wanted a polygon of 17 sides (heptadecágone) to appear on his tombstone.
• 17 is the sum of two squares 4²+1², being a cousin of the form 4k+1 (k, integer), also divides to a sum of squares 9² +2²
• Strong cousin number.
• It's a pioneering number.
• It's a prime number from Eisenstein.
• 17 is the number of possible types of symmetries in the plane

Science

• It's the atomic number of chlorine.
• In the periodic table, group 17 represents halogens.
• Messier M17 is an HII region in the constellation of Sagittarius.
• Object of the New General Catalog NGC 17 is a spiral galaxy in the constellation Cetus.
• 17P/Holmes is a periodic comet of the solar system.
• (17) Thetis is an asteroid that forms part of the asteroid belt.

In culture

Ranging 17 on the Alitalia planes.

• In Italy, 17 is the number of bad luck. This is because, in the Roman numeration, 17 is written XVII, which is an anagram of VIXIwhich means "I've lived."I mean, "I'm dead."in Latin. That's why the Italian buildings don't have a 17th floor, the hotels don't have room 17 and the Alitalia planes have no row 17. When the Renault brand exported its R17 model to Italy, it was traded there with the name "Renault R177".
• In France, it's the police phone number
• In the novel Cien years of solitude, of the Nobel Prize in Colombian Literature Gabriel García Márquez, is the number of children of Colonel Aureliano Buendía.
• It's agent's number 17 alter ego of agent 47 of the Hitman video game.
• In the Harry Potter series, 17 silver snouts are equivalent to a golden hen. This is also the price of a dragon liver ounce. At the same time, at the age of 17 it is when the older teachers are considered.
• In the video game Half-Life 2, the city where the plot is developed is called city 17.
• In Dragon Ball Z, it corresponds to the male android that makes its appearance in the cell saga.
• In 2019, the film was released on Netflix Seventeen directed by Daniel Sánchez Arévalo.