To be completely serious, the final book of the bible was a response to current events of the time. The numbers 666 were used to represent Emperor Nero, the "beast", and this is supported by the Hebrew's regular use of numerology (Gematria).

This is how we also know that it might've been a "mistranslation" when the bible says 666, because in Hebrew gematria, 666 is equal to nrwn qsr (Neron Cesear), whereas 616 is equal to nrw qsr (Nero Cesear).

The usage of 6 to refer to Satan (directly translated to just "The Adversary") does not mean that a series of 666's is evil. It's used to mean that the adversary will never be a "perfect 7". Jesus' gematria in greek is a series of 8's (888), to indicate that he surpasses the "perfect 7."

No, 666 is not the devil's number. Yes, 666/616 finds its' way in the bible. No, it was not used to reference the devil. Yes, it was used to reference Emperor Nero, who was considered by Christians to be evil, without alerting Nero or his supporters.

Side note, I honestly think it's highly disrespectful to dumb down the numbers to "omg EvULLL!" when there was so much more thought put into it. Like, these people developed an intricate numerological language based on addition, used it to safely reference current events while fearing for their lives, and you're going to spit in their face and dumb it down to "ZOMG DEBUL NUMBAH!!!"? Wow.