I took number theory this semester and loved it but don't feel like I learned all that much. I am not going any farther in formal education in math so I would like to further investigate number theory on my own. Do you have any suggestions for good books? I need at least one that is pretty basic and preferably one that goes a little bit more advanced. (You can look at some of my other recent questions to see the level that I'm at, but I really don't understand much beyond Diophantine equations- pretty much have to start over).
Thanks for the help and I apologize if this question is too broad/vague/or subjective.