Twelve (12) is a positive integer one more than 10 and one less than 12.
12 is a highly composite number, meaning it has more factors than any lesser number (it has 6 factors). The previous highly composite number is 6, and the next is 24.
12's factorization is 2^2*3.
12 is the number of items in a dozen.
Being highly divisible, 12 shows up frequently, being the number of hours on a typical clock.
12 is the first abundant number, that is, its proper divisors add up to more than itself. The next abundant number is 18.