account number
Refers to a bank account number or similar financial account identifier.
Please tell me the account number for the transfer.
The account number is written on the cover of the passbook.
Please enter the recipient's account number.
Let's double-check the account number before sending the money.
I gave our business partner our account number.
I mistyped one digit of the account number and sent the money to the wrong place.
口座 means the bank account itself, while 口座番号 is the specific number that identifies that account.
番号 is a generic word for any number (phone, ticket, etc.), while 口座番号 refers specifically to a bank account's identifying number.
Compound of 口座 (account) and 番号 (number).