One hundred five

One hundred five (also One hundred and five) (105, CV) is the natural number following one hundred four and preceding one hundred six. It is a triangular number as well as a composite number, with its divisors being 3, 5, 7, 15, 21 and 35, and its factorization:

makes it a sphenic number. This is one of the few odd numbers to be immediately surrounded on both sides by twin primes (101 and 103, below, and 107 and 109 above). The only other such odds less than a thousand are 15, 195 and 825. They are even rarer after that.

One hundred five is also:

• The atomic number of hahnium, also known as dubnium.
• The designation of some spur routes of Interstate 5.
• A film format introduced by Kodak for their first folding camera. See 120_film.

This article is about the number. For the year AD 105, see 105.