Can credit card account numbers be changed when the account is sold?

Answer 1

Yes and no, it depends on the transaction. If the account number has changed, the bank will send you a notification and a new card with instructions. The bank will never randomly close your account, or ask you to provide any account numbers.

Answer 2

If you are asking this because your credit card account was charged off and sold to a collection agency who is reporting the account with a different account number - the account number the collection agency reports is usually their own internal account number and not the credit card account number.

If you are asking because your current and in good standing credit card account was sold/transferred to another company, then the new company may or may not change the account number. They would inform you and issue you a new card if the account number is changed.

I don't think I've ever heard of a single current in good standing credit card account being sold/transferred.
If it happens it usually happens to all of the accounts the creditor holds and it usually only happens if the current creditor gets bought out, sells/transfers their whole credit card portfolio, etc.