How many colleges should I apply to?

I’m going to apply in the fall, and all of my applications will be regular (not early). Right now I have 6 colleges on my list, but I don’t know if I should bring the number down. I’m looking at Boston U., Northeastern U., Syracuse U., Univ. of Arizona, Colorado State U., and Hofstra U., and I feel pretty confident in getting into all of them. Any suggestions for the number I should apply to?