bank electronic infrastructure and public-key cryptography

Hi, can anyone fill me in on a little naivette on my part:
when a bank uses public key cryptography, is the public key the same
for everyone? I heard of a bank that posts their public-key on their
web site. It seems strange that one number can be factored into two
different prime keys for each account holder. Can anyone please fill me
in on how the banks use this encryption technique, and how other
cyphers are used in tandem?

Sincerely,
Received on Fri Dec 23 20:11:08 2005