It all depends
The number of schools is less important than making sure you have a great mix of schools. Have you selected colleges that meet your needs academically and socially? Assuming you have, I usually recommend having 2-3 colleges in each category of enrollment expectation--reach, target, and safety. Though, of course, many students will have more or fewer on their list. Generally, students who are able to visit colleges ahead of time will have fewer on their application list than those who won't be visiting in person until after they receive acceptances.
I also recommend making sure that your safety schools are all colleges you'd enjoy attending. (I define a safety school is one where your grades and test scores are above the middle 50% for that college and where the college accepts at least half the applicants...and remember that these are also the colleges where you have the best chance of receiving merit aid).