Binary: 101101

Septimal (base 7): 63

Octal: 55

Hexadecimal: 2d

Base 24: 1L

45 = 3 × 3 × 5

45 has 6 divisors: 1, 3, 5, 9, 15, 45

Sum of all divisors other than 45: 33

Sum of 2 squares: 45 = 6² + 3²

Difference of 2 squares: 45 = 7² - 2² = 9² - 6² = 23² - 22²

45 is a triangular number
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The next triangular is: 55

45 is a hexagonal number

45 is a palindromic number in binary system (101101)

The 45th prime number is: 197

Previous prime number: 43 — Next prime number: 47