While this is not an answer to your question but why do you need that. Based on my opinion storing anything but stream of characters (Integer, decimal values, etc.) into strings is bad.
Why bad? Becouse in most ocasions you waste more space. For instance:
storing 2147483647 in numerical type would require you 32 bits (4 bytes) of space. Note that number is actually Maximum 32 bit integer.
storing 2147483647 as series of characters(string) would require 80 bits (10 bytes) of space provided that you save it in AnsiChar string also known as AnsiString. Saving it in Unicode format would require even more space