When defining datatypes in a database, I have always had a problem with choosing whether to use integers or strings to store certain \'numerical\' data.
I don't use a numerical data type unless I expect to do math on the data. Why risk finding a problem in the future for something that you were "sure" would always be a number that someone decides to put a non-numeric character in.
If you aren't going to do math on it make it a string.