33 (number) explained

Number:33
Divisor:1, 3, 11, 33

33 (thirty-three) is the natural number following 32 and preceding 34.

In mathematics

33 is the 21st composite number, and 8th distinct semiprime (third of the form

3 x q

where

q

is a higher prime).[1] It is one of two numbers to have an aliquot sum of 15 = 3 × 5 — the other being the square of 4 — and part of the aliquot sequence of 9 = 32 in the aliquot tree (33, 15, 9, 4, 3, 2, 1).

It is the largest positive integer that cannot be expressed as a sum of different triangular numbers, and it is the largest of twelve integers that are not the sum of five non-zero squares;[2] on the other hand, the 33rd triangular number 561 is the first Carmichael number.[3] [4] 33 is also the first non-trivial dodecagonal number (like 369, and 561)[5] and the first non-unitary centered dodecahedral number.[6]

It is also the sum of the first four positive factorials, and the sum of the sum of the divisors of the first six positive integers; respectively:\begin 33 & = 1! + 2! + 3! + 4! = 1 + 2 + 6 + 24 \\33 & = 1 + 3 + 4 + 7 + 6 + 12 \\\end

It is the first member of the first cluster of three semiprimes 33, 34, 35; the next such cluster is 85, 86, 87.[7] It is also the smallest integer such that it and the next two integers all have the same number of divisors (four).[8]

33 is the number of unlabeled planar simple graphs with five nodes.[9]

There are only five regular polygons that are used to tile the plane uniformly (the triangle, square, hexagon, octagon, and dodecagon); the total number of sides in these is: 3 + 4 + 6 + 8 + 12 = 33.

33 is equal to the sum of the squares of the digits of its own square in nonary (14409), hexadecimal (44116) and unotrigesimal (14431). For numbers greater than 1, this is a rare property to have in more than one base. It is also a palindrome in both decimal and binary (100001).

33 was the second to last number less than 100 whose representation as a sum of three cubes was found (in 2019):[10] 33 = 8866128975287528 ^ + (-8778405442862239)^ + (-2736111468807040)^.

33 is the sum of the only three locations

n

in the set of integers

\{1,2,3,...,n\}\inN+

where the ratio of primes to composite numbers is one-to-one (up to

n

) — at, 9, 11, and 13; the latter two represent the fifth and sixth prime numbers, with

9=32

the fourth composite. On the other hand, the ratio of prime numbers to non-primes at 33 in the sequence of natural numbers

N+

is

\tfrac{1}{2}

, where there are (inclusively) 11 prime numbers and 22 non-primes (i.e., when including 1).

Where 33 is the seventh number divisible by the number of prime numbers below it (eleven),[11] the product

11 x 33=363

is the seventh numerator of harmonic number

H7

, where specifically, the previous such numerators are 49 and 137, which are respectively the thirty-third composite and prime numbers.[12] [13]

33 is the fifth ceiling of imaginary parts of zeros of the Riemann zeta function, that is also its nearest integer, from an approximate value of

32.93506\ldots

[14] [15] [16]

Written in base-ten, the decimal expansion in the approximation for pi,

\pi3.141592\ldots

, has 0 as its 33rd digit, the first such single-digit string.[17]

A positive definite quadratic integer matrix represents all odd numbers when it contains at least the set of seven integers:

\{1,3,5,7,11,15,33\}.

[18] [19]

In science

Astronomy

In technology

In religion and mythology

In sports

In media

In other fields

Thirty-three is:

See also

External links

Notes and References

  1. A001748.
  2. 2023-10-09 .
  3. 2023-11-15 .
  4. 2023-11-15 .
  5. 2024-02-24 .
  6. 2024-01-12 .
  7. A056809.
  8. 2024-02-27 .
  9. 2024-01-12 .
  10. Andrew R.. Booker . Cracking the problem with 33 . 2019 . math.NT . 1903.04284 .
  11. 2024-05-30 .
  12. 2024-01-12 .
  13. 2024-01-12 .
  14. 2024-06-01 .
  15. 2024-06-02 .
  16. Web site: Odlyzko . Andrew . Andrew Odlyzko . The first 100 (non trivial) zeros of the Riemann Zeta function [AT&T Labs]]. Andrew Odlyzko: Home Page . . 2024-01-16 .
  17. 2024-05-30 .
  18. Book: Cohen . Henri . Number Theory Volume I: Tools and Diophantine Equations . Consequences of the Hasse–Minkowski Theorem . . . 239 . 1st . 2007 . 312–314 . 10.1007/978-0-387-49923-9 . 978-0-387-49922-2 . 493636622 . 1119.11001 .
  19. 2023-10-09 .
  20. Web site: Williams . Matt . What is the asteroid belt? . . Science X . August 24, 2015 . 2023-09-22 .
  21. Insights #517, October 8, 2010.
  22. Book: de Vries, Ad. Dictionary of Symbols and Imagery. 1976. 462. North-Holland Publishing Company. Amsterdam. 978-0-7204-8021-4.
  23. Web site: Imam Gazzali's Ihya Ulum-id-din: pt. 1 and 2. The book of constructive virtues. Ghazzālī. Fazlul. Karim. 1978. Sind Sagar Academy. 21 March 2018. Google Books.
  24. Book: Sharp, Damian . Simple Numerology: A Simple Wisdom book (A Simple Wisdom Book series) . Red Wheel . 2001 . 7 . English . 978-1573245609 .
  25. Web site: Dedicated umpire stayed at the plate for 32 innings. - Free Online Library. 2020-08-21. www.thefreelibrary.com.
  26. Web site: Cary. Tim. 2015-02-14. 10 of the Longest Winning Streaks in Sports History. 2020-08-21. Sportscasting Pure Sports. en-US.
  27. Web site: THE 33 British Board of Film Classification. 2020-08-21. www.bbfc.co.uk.
  28. Web site: Russian Language Alphabet - listen online and practice pronunciation. 2020-08-21. Russian Step By Step Books Natasha Alexandrova. en-US.
  29. Web site: Georgian Alphabet Georgian Language, Alphabet and Pronunciation. 2020-08-21. www.ocf.berkeley.edu.