How many colors are there in the world? which colors are primary colors? are all colors happy colors?

There are about 16.8 million colors.

The primary colors are red yellow and blue, although some people use: cyant,  magenta and yellow.

Not really, although it depends upon the person. Blue to me is a sad color, but to some people it would be a happy color. depends upon the person.

Great questions, hope i helped!