12's factorization is 22*3.
A set of 12 objects is often called a dozen. That type of set gets its own name because many things are grouped in twelve: for example, twelve months in a year, twelve inches in a foot, twelve eggs in a typical container, etc.
There are 12 size-3 Latin squares.
In googology Edit
In Greek-based number-naming systems, 12 is associated with prefix "dodeka-", and with prefix "duodec-" in Latin systems.
Being highly divisible, 12 shows up frequently, being the number of hours on a typical clock.