145 (number)
145 (one hundred [and] forty-five) is the natural number following 144 and preceding 146.
In mathematics
- Although composite, 145 is a Fermat pseudoprime in sixteen bases with b < 145. In four of those bases, it is a strong pseudoprime: 1, 12, 17, and 144.
- the Mertens function returns 0.[1]
- 145 is a pentagonal number[2] and a centered square number.[3]
- . 145 is the fourth number that is the sum of two different pairs of squares. Also, 145 is the result of 34 + 43, making it a Leyland number.
- , making it a factorion.[4] The only other numbers that have this property are 1, 2 and 40585.[4]
- , making 145 the smallest number that can be written as the sum of a square number and a factorial in 3 ways. The next number with this property is 46249.[5]
References
- Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 140