This "classification" is pretty much a tautology and provides no information. The enumeration of all subgroups of a cyclic group and their orders is one of the most basic facts in all of group theory and known by pretty much everyone who has studied the subject at all. Thus, I'm completely failing to see the point in any of this.
It was more to provide a hopefully new perspective on some existing problems in number theory.
Then nice try I guess, but there is nothing remotely new about any of this. You're not going to find a new perspective on something in math using a completely routine application of a well-known theorem. You'll need to either work really hard or come up with a genuinely new idea, and probably both.
I disagree. Math is all about applying well-known theorems to existing problems.
I don't understand how using group-theory language to describe number-theoretic properties provides extra insight in this case (e.g. conjecture: all perfect numbers are even is more concise than the group-theoretic description given in the page). Can you expand on why you believe the tools of group theory have something to say about this?
(e.g. for polynomial roots, the connection with symmetry groups comes from symmetries of factorized polynomials, while there's no obvious-to-me connection here as there is no unique-up-to-symmetry integer factorization)
I just found it interesting that certain problems in number theory could be rephrased as problems about cyclic groups. Maybe it could potentially make some easier to solve.