45 (number)

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444546
Cardinalforty-five
Ordinal45th
(forty-fifth)
Factorization32· 5
Divisors1, 3, 5, 9, 15, 45
Roman numeralXLV
Binary1011012
Ternary12003
Quaternary2314
Quinary1405
Senary1136
Octal558
Duodecimal3912
Hexadecimal2D16
Vigesimal2520
Base 361936
 
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444546
Cardinalforty-five
Ordinal45th
(forty-fifth)
Factorization32· 5
Divisors1, 3, 5, 9, 15, 45
Roman numeralXLV
Binary1011012
Ternary12003
Quaternary2314
Quinary1405
Senary1136
Octal558
Duodecimal3912
Hexadecimal2D16
Vigesimal2520
Base 361936

45 (forty-five) is the natural number following 44 and followed by 46.

In mathematics[edit]

Forty-five is a triangular number, and in particular the sum of all the decimal digits (0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45). It is the smallest triangle number (after 1) which can be written as the sum of two squares. It is also a hexagonal and 16-gonal number,

45 is the sixth positive integer with a prime factorization of the form p2q, with p and q being prime.

33 is the aliquot sum of 45 and the aliquot sequence of 45 is (45, 33, 15, 9, 4, 3, 1, 0).

Since the greatest prime factor of 452 + 1 = 2026 is 1013, which is clearly more than 45 twice, 45 is a Størmer number.

In base 10, it is a Kaprekar number, and a Harshad number.

In science[edit]

Astronomy[edit]

In music[edit]

In other fields[edit]

Forty-five may also refer to:

References[edit]

  1. ^ Arthur Hill Cash (2007), John Wilkes: The Scandalous Father of Civil Liberty, Yale University Press, p. 219, ISBN 978-0-300-12363-0