I'm not aware for 7 or numbers in general, I do understand that "superstition" means things like irrational actions or religious beliefs.
I'm not a superstitious person myself, meaning I don't really believe in magic, or even have much for religious beliefs.
Is 7 considered lucky? 7? as in the number between 6 and 8? Correct.     A lot of people are superstitious about numbers.
''Superstition'' also refers to religious beliefs or actions arising from irrationality.