Encrypt credit card numbers

[nimasdj]

Thanks, since it has nothing to do with CC anymore, I created a new thread, please advice this one:

What is the difference of AES-128 and AES-512 using php's mcrypt?

I am confused about the difference of AES-128 and AES-512 using php’s mcrypt. The difference is just the length of the key (32 and 64 characters) or the difference is the used algo such as MCRYPT_RIJNDAEL_128? If the difference is the latter, how should be the algo for AES-512?