Yoruba's number meaning

I'm studying Yoruba mythology.
I want to know why Yoruba likes 7, 16, and 6.

In Yoruba mythology, seven stands for goddess Emaya.
16 means 16 keys that open the door to the future.
It is said that "Fa" sees everything that happens in the world with 16 eyes.
The feast day of "the god of the mountain" is December 4, and his special favorite number is said to be '6.

Where do 7, 16, and 6 come from, so are the numbers that the gods like in Yoruba mythology?