5424 is also used outside of Citibank as my old debit card (with a MasterCard logo) from Fifth Third Bank started with 5424. I don't believe they're affiliated

5424 is also used outside of Citibank as my old debit card (with a MasterCard logo) from Fifth Third Bank started with 5424. I don't believe they're affiliated with Citibank, but I could be mistaken.