 105 (number)

105 (one hundred [and] five) is the natural number following 104 and preceding 106.
105 Cardinal one hundred [and] five Ordinal 105th
(one hundred [and] fifth)Numeral system 105 Factorization Divisors 1, 3, 5, 7, 15, 21, 35, 105 Roman numeral CV Binary 1101001_{2} Octal 151_{8} Duodecimal 89_{12} Hexadecimal 69_{16} Contents
In mathematics
105 is a triangular number, a 12gonal number and a Zeisel number. It is a sphenic number, and is the product of three consecutive prime numbers. 105 is the double factorial of 7. It is also the sum of the first five square pyramidal numbers.
105 comes in the middle of the prime quadruplet (101, 103, 107, 109). The only other such odd numbers less than a thousand are 15, 195 and 825. 105 is also a pseudoprime to the prime bases 13, 29, 41, 43, 71, 83 and 97. The distinct prime factors of 105 add up to 15, and so do those of 104, hence the two numbers form a RuthAaron pair under the first definition.
105 is also a number n for which n − 2^{k} is prime, for 0 < k < log_{2}(n). (This even works up to k = 8, ignoring the negative sign.)
105 is the smallest integer such that the factorization of x^{n} − 1 over Q includes coefficients other than .
In science
 The atomic number of hahnium, also known as dubnium.
In other fields
105 is also:
 The number of surat alFil in the Qur'an.^{[citation needed]}
 A simple card game where players lose if they have over 105 points.
See also
References
 Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 134
Categories: Integers
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