In Mathematics
Forty-five is a triangular number, a hexagonal and 16-gonal number, a Kaprekar number, and a Harshad 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.
The sum of all the digits is 45 (0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45).
Read more about this topic: 45 (number)
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—George Bernard Shaw (1856–1950)
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