yes it is. And I don't know how you could say that pi isnt 3.14... because every equation that has ever used pi has been correct.
PI is a very simple number used to describe the shape characteristics of a circle. It is not a magic number that is up for debate. Therefore saying that "What if PI is actually not PI" is an argument a stoner would make.
There are other numbers in math that are constants and are used to describe the environment. e, Avogadro's number, acceleration due to gravity, etc. This is what gives basics number math application in the world.
The manupliation of this data usually in the form of proofs is what gives math its power.
Basically math is a way for humans to quantify, explain, and visualize the mechanisms in their world.