79 (number)

79 (seventy-nine) is the natural number following 78 and preceding 80.

In mathematics

79 is:

• An odd number.
• The smallest number that can not be represented as a sum of fewer than 19 fourth powers.
• A strictly non-palindromic number.^[1]
• The 22nd prime number (between 73 and 83)
• The smallest prime number p for which the real quadratic field Q[√p] has class number greater than 1 (namely 3).^[2]
• A cousin prime with 83.
• An emirp, because the reverse of 79, 97, is also a prime.^[3]
• A Fortunate prime.^[4]
• A circular prime.^[5]
• A prime number that is also a Gaussian prime (since it is of the form 4n + 3).
• A happy prime.^[6]
• A Higgs prime.^[7]
• A Kynea prime (having the form (2n + 1)² − 2).^[8]
• A lucky prime.^[9]
• A permutable prime, with ninety-seven.
• A Pillai prime,^[10] because 23! + 1 is divisible by 79, but 79 is not one more than a multiple of 23.
• A regular prime.^[11]
• A right-truncatable prime, because when the last digit (9) is removed, the remaining number (7) is still prime
• A sexy prime (with 73).
• The n value of the Wagstaff prime 201487636602438195784363.

In science

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

In astronomy

• 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

Planet Jupiter has 79 moons.

In other fields

• Live Seventy Nine, an album by Hawkwind
• The years 79 BC, AD 79 or 1979
• The number of the French department Deux-Sèvres

References