Hello Godavari,
Yes, Marseel answer is correct. FIBAN t code data is saved in TIBAN table. Update the data in FIBAN t code through SM30. Please check the same in TIBAN table via SE16.
Also pls go through this link once.
http://scn.sap.com/people/pere.diaz/blog/2005/07/19/about-the-iban-international-bank-account-number
I hope it helps!
Thanks & Regards,
Lakshmi S