45 (forty-five) is the natural number following 44 and followed by 46. Cardinal45forty-five Ordinal45thforty-fifth Factorization 3^2 cdot 5 Divisors 1, 3, 5, 9, 15, 45 Roman numeral XLV Binary 101101 Hexadecimal 2D 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 s… (More on Xlv)