This is the “number of the beast” and not his mark, as is plainly stated in Rev. 13:16-18. There will be three things men will have a choice of taking in the days of Antichrist: the mark of Antichrist, his name, or the number of his name. What the Antichrist’s name and mark will be is not stated; but the number of his name is stated as being 666. Therefore, no man can now know his name or his mark and will never be able to know them until the Antichrist comes after the Rapture of the Church, as we shall see. However, anyone now can know that 666 is the number of his name, as this is revealed in Rev. 13:18.

Finis J. Dake, God’s Plan for Man, (Lawrenceville, GA: Dake Publishing, Inc., 1949), 75.
https://www.dakebible.com