93 (number)

In mathematics

93 is:

• the 28th distinct semiprime and the 9th of the form (3.q) where q is a higher prime.
• the first number in the 3rd triplet of consecutive semiprimes, 93, 94, 95.
• with an aliquot sum of 35; itself a semiprime, within an aliquot sequence (93,35,13,1,0) of three numbers to the Prime 13 in the 13-Aliquot tree.
• a Blum integer, since its two prime factors, 3 and 31 are both Gaussian primes.
• a repdigit in base 5 (3335), and 30 (3330).
• palindromic in bases 2, 5, and 30.
• a lucky number.
• a cake number.
• an idoneal number.

There are 93 different cyclic Gilbreath permutations on 11 elements, and therefore there are 93 different real periodic points of order 11 on the Mandelbrot set.

In other fields

93 is:

• The atomic number of neptunium, an actinide.
• The code for international direct dial phone calls to Afghanistan.
• The number of the FIRST Robotics team, NEW Apple Corps.
• One of two ISBN Group Identifiers for books published in India.
• The number of the French department Seine-Saint-Denis, a Paris suburb with high proportions of immigrants and low-income people, and as such used by many French rappers and those emulating their speech.

In classical Persian finger counting, the number 93 is represented by a closed fist. Because of this, classical Arab and Persian poets around 1 CE referred to someone's lack of generosity by saying that the person's hand made "ninety-three".

References

References

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10. (2012). "Magical Mathematics: the mathematical ideas that animate great magic tricks". Princeton University Press.
11. "Home {{!}} nacteam93.com".
12. Durand, Alain-Philippe. (2002). "Black, Blanc, Beur: Rap Music and Hip-Hop Culture in the Francophone World". Scarecrow Press.
13. (March 2006). "Spitting Fire". [[Spin (magazine).
14. Bloom, Jonathan M.. (Spring 2002). "Hand sums: The ancient art of counting on your fingers". Boston College Magazine.
15. Campbell, Colin D.. (2018). "Thelema: an introduction to the life, work & philosophy of Aleister Crowley".