The difference between mathematics and numerology

Numerologist is a four-letter word among mathematicians ( I can imagine ). Is numerology the same as number theory? Not really, the difference between numerology and number theory, as a branch of mathematics, can best be explained using an example.

Both numerologists and mathematicians study identities like $$2^2 + 3^2 + 5^2 + 7^2 + 11^2 + 13^2 + 17^2 = 666.$$ A mathematician would notice that this is the sum of the first seven primes and rewrite the sum as $$\sum_{k=1}^{7} p_k = 666.$$ The right-hand side sum is a number with equal digits, so the mathematician might look at other sums of consecutive primes and verify if these sums have similar patterns. Basically a mathematician is interested in anything that might lead to the formulation of a theorem, a proposition to prove mathematically.

A numerologist would immediately notice that $666$ is the number of "The Beast", the representation of evil in the Christian belief system. Then, a numerologist might consider prime numbers divine, since they are the building blocks of all integers, and might try to formulate some law of good and bad represented in the sum-formula. Numerologists also believe that future events can be predicted so they will be extra alert to that.

I believe that it was until the Middle Ages that there was no real distinction between the profession of numerologist and mathematician. Newton has been called the last Alchemist, perhaps he was the last mathematician / numerologist as well. ( History, I am afraid, is not my strongest point. )