2

The number two (2) is the second Positive Integer and the first Prime Number. It is Even, and is the only Even Prime (the Primes other than 2 are called the Odd Primes). The number 2 is also equal to its Factorial since $2!=2$. A quantity taken to the Power 2 is said to be Squared. The number of times $k$ a given Binary number $b_n\cdots b_2 b_1 b_0$ is divisible by 2 is given by the position of the first $b_k=1$, counting from the right. For example, $12=1100$ is divisible by 2 twice, and $13=1101$ is divisible by 2 zero times.

See also 1, Binary, 3, Squared, Zero