105 (number)
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105 is a natural number that comes after 104 and before 106. It is an odd number, meaning it cannot be divided by two. It is also a composite number, as it has divisors other than 1 and itself.
In Roman numerals it is written CV. In binary it is 1101001, and in hexadecimal it is 69.
Mathematical properties
The prime factorization of 105 is 3 × 5 × 7. It is therefore a sphenic number—one that results from the multiplication of three distinct primes. Its divisors are 1, 3, 5, 7, 15, 21, 35, and 105, a total of eight divisors.
The sum of its divisors less than the number itself (1+3+5+7+15+21+35) equals 87, which is less than 105. This makes it a deficient number.
Triangular number
105 is a triangular number: it is the sum of the integers from 1 to 14 (1+2+3+…+14 = 105). It is also equal to 7!! (the double factorial of 7), which is 7 × 5 × 3 × 1.
Other uses
105 is used in various conventional contexts such as dates, transport codes, and different measurements. These particular uses depend on the system or body responsible for numbering and have no specific mathematical significance.