No, account number is not written on Debit or Credit Cards. Debit and Credit Cards do have 16 digits card number, expiry date, Card Holder's name and Card Verification Value or CVV or CVC at the back which is a three digit number. While making payment online through Debit or Credit cards, you have to enter the card number, expiry date [ written in the format- MM/YY ] and necessarily the CVV. Sometimes, they also ask for Card Holder's name. Then by clicking on Proceed, you'll receive an One Time Password on the registered mobile number of the card which you have to enter where it is required and make your payment.