American Express Features

• - They have 15 digits.
• - Can be validated using the Luhn algorithm.
• - Are actively issued.

Issuer identification number (IIN)

The IIN identifies the card issuing institution that issued the card to the card holder. American Express credit cards begin with the following prefixes: 34, 37.

Major Industry Identifier (MII)

The first digit of your credit card number is known as the Major Industry Identifier (MII). This represents the category of industry which issued your credit card. The MII for American Express credit cards is 3 which means they belong to the Travel and entertainment category.