The 666 is so cryptic, I don't know that there's anything helpful to say about it in this time. Perhaps it suffices just to recognize that what it means won't matter until after the Rapture, when it's used as a mark of submission. Prior to that it's anyone's guess, and after that it will only be of usable consequence to the Jews. So much for gematria.
What more can I say about the King of the North? It really is self-explanatory.
The reference to a martial god, on the other hand, could use some unpacking. It aligns quite well with the god of Islam, and really, no other. Allah is a god of conquest and siege who was unknown in the days of Daniel. Since no other god before or since could really fit the entirety of this description, the Antichrist will be a nominal Muslim.
He will succeed politically through the auspices of Islam. It may be that he initially sees himself as the Mahdi (I think others will), but eventually, he will come to see himself as god. The Islamic world will gravitate toward him, and much of the rest of the world will be bowled over by him and his violent impulse. Resistance will be seen as futile, while spiritual delusion will seal the deal.
With all true Gentile believers removed from the scene through the Rapture, the only people that will withstand the delusion and offer any resistance (particularly to the mark) will be the Jews. For anyone not willing to go along with his rule, his religion, and his economy, their heads will be taken. That that is a a penchant seen readily amongst radicalized Muslims today is no mere coincidence, its seems to me, so the details converge and tell me the Antichrist is a Muslim who will rise to power in the area that's at war this very day.