79 (number)

79 is:

• Anodd number.
• The smallest number that can not be represented as a sum of fewer than 19 fourth powers.
• The 22nd prime number (between 73 and 83)
• An isolated prime without a twin prime, as 77 and 81 are composite.^[1]
• The smallest prime number p for which the real quadratic field Q[√p] has class number greater than 1 (namely 3).^[2]
• Acousin prime with 83.
• Anemirpinbase 10, because the reverse of 79, 97, is also a prime.^[3]
• AFortunate prime.^[4]
• Acircular prime.^[5]
• A prime number that is also a Gaussian prime (since it is of the form 4n + 3).
• Ahappy prime.^[6]
• AHiggs prime.^[7]
• Alucky prime.^[8]
• Apermutable prime, with ninety-seven.
• APillai prime,^[9] because 23! + 1 is divisible by 79, but 79 is not one more than a multipleof23.
• Aregular prime.^[10]
• Aright-truncatable prime, because when the last digit (9) is removed, the remaining number (7) is still prime.
• Asexy prime (with 73).
• The n value of the Wagstaff prime 201487636602438195784363.
• Similarly to how the decimal expansion of 1/89 gives Fibonacci numbers, 1/79 gives Pell numbers, that is, ${\displaystyle {\frac {1}{79}}=\sum _{n=1}^{\infty }{P($n)\times 10^{-(n+1)}}=0.0126582278\dots \ .}  
• ALeyland number of the second kind.

• The atomic number of the chemical element gold (Au) is 79.

• Messier object 79 (M79), a magnitude 8.5 globular cluster in the constellation Lepus
• New General Catalogue object 79 (NGC 79), a galaxy in the constellation Andromeda

• Live Seventy Nine, an album by Hawkwind
• The years 79 BC, AD 79or1979
• The number of the French department Deux-Sèvres
• The ASCII code of the capital letter O

•   Media related to 79 (number) at Wikimedia Commons