Most of Citi's leading credit cards offer virtual account numbers, including the Citi Double Cash Card. More widely known as virtual credit card numbers, virtual account numbers are randomly generated, temporary credit card numbers that you can use while shopping online to protect your real account number. Citi is one of the few major issuers that still offer virtual card numbers. Capital One also provides virtual credit card numbers through its Eno assistant tool, but many issuers no longer offer this extra security layer since mobile wallets essentially accomplish the same function.