Why is the number 12 so prominent?
In the world. Religion being key.
Numbers are symbols for many groups. For the Lakota Tribe, 4 was a recurring number. It was believed that 4 souls left the body when somebody died. Wankan Tanka referred to 16 main deities, which is a multiple of 4. The number 4 was important to them because it symbolized the North, South, East, and West.
Mathematically speaking it's a convenient number as it is easily divisible by 2, 3, 4, and 6. In the Judeo-Christian tradition there were twelve tribes in ancient Israel and Jesus had twelve apostles