The idea that there is "power" in a number is very much a New Age idea, although there is nothing particularly new about the New Age. But the idea that the Bible itself is secretly trying to communicate to us this powerful number...that's gnosticism.
Gnosticism has been around for as long as the Scriptures. From the very moment that God gave His people His Word, there have been certain numbers of them who have been trying to figure out what that Word "really" means, what kinds of hidden messages it carries, as though buried somewhere deep within the plain and obvious truth that God's given us is the "real" truth that He wants us to have.
We just have to know how to read it to get there.
You might say that the Pharisees were involved in this a little bit, spending the bulk of their lives trying to clarify what the law really meant, expanding on the interpretation of it, and creating an entire set of rules that God never gave His people and calling them holy.
But the idea of gnosticism is not really interpreting the Scriptures in a certain way, like the Pharisees did; it's more about reading into the Scriptures ideas that were never there in the first place. Instead of trying to determine what the Scriptures "really" say, gnostics derive their meaning from what is not said, but what they believe is still meant.
That's why gnostic ideas are so dangerous to a living faith - they sound very legitimately like they could be drawn from the Scriptures in some tangential way. They sound very legitimately like they come from persons who have invested a lot in discovering these "truths" in the Scriptures. Quite often, gnostics can quote you down a trail of Scripture as "evidence" of whatever it is that they're proposing, and then add that through a "divinely-inspired" reading of these passages privy only to them, they uncovered this hidden truth that is really at the heart of God's message.
It's the kind of stuff that when you first hear it, makes you go, "Whoa...."
This is where a little bit of discernment goes a long way. It may be that you can take a thousand different turns through the pages of God's Word and come out at the place where the gnostics are trying to lead you, but God says that His path is straight; you don't have to take a single turn to get to truth. It's right there.
It may be that if you put enough pieces together, you can uncover some secret, hidden message in the Scriptures, but God's message has always been plain and clear. He's never kept secrets and never hidden messages. His prophets never had to decipher a code. His disciples didn't have to trace it through. It's always been right out there in the open. The God who is Truth makes Himself known clearly and plainly and always has, from the very first day when He walked in the Garden with Adam and Eve.
There's this incredible tension in all of this - we all want to be persons who are in on some kind of secret, who know something that the rest of the world doesn't know, who have figured out the "key" to life, as though it were some sort of mystery and yet, the God that we love (and Who loves us) has spoken the secret plainly out loud. He's given us the key right in front of everyone. There's nothing secret about the mystery of God, even though there is much that we still cannot understand.