Yes. Mecca. Isis is not a city but she does sit in Mecca. The Kaaba was said to be the house of Allat (femaie version of Allah) before Islam. Islam has adopted Allat as Allah. Allat was the name of Isis by the Arabians. Isis also had these names... "the mother of all gods [abominations]", the "queen of the throne of Heaven", "courtesan [harlot] of the gods"
The exact connection of 666 to the name of the antichrist is a mystery to me. However, the number 666 is directly connected to gematria. Gematria was the technique that magicians of Assyria and Babylon (maybe even Egypt) used to tell the future. It is a form of numerology and is associated with the worship of the heavens. Here is an ancient tablet of a solar seal dedicated to the worship of the heavens (note the sum of the vertical and horizontal entires as shown):
View attachment 91397
One claim that has been considered by others is that geomatria would spell out the antichrist's name.
Personally, I find it hard to believe that John would use ancient magic techniques and so I don't believe this to be the case.