A hundred and nine is prime and reduces to ten and then one. It is one of the primes past the hundred that the older systems left undeveloped, and it carries no traditional religious symbolism. What can be said of it is structural only.
A hundred and nine is prime, with no factors beyond one and itself. It is a twin prime, paired with 107, a prime just two away. Because it leaves a remainder of one when divided by four, it is a Pythagorean prime, expressible as a sum of two squares: 3 squared plus 10 squared.
Nicomachus's own arithmetic sorted whole numbers into deficient, perfect and abundant by comparing them with the sum of their own divisors, a genuinely ancient classification that has nothing to do with the letter charts later numerologists built; the modern system that assigns meaning to digit sums is a distinct, twentieth-century construction that happens to borrow the Pythagorean name.
None of this genealogy is hidden by the numerologists themselves: Balliett, Campbell and Jordan each wrote openly as originators and systematisers rather than as transmitters of a secret ancient science, and the chain from Balliett's 1908 book through Campbell's 1931 manual to Jordan's 1965 standardisation is well documented in the numerology literature's own bibliographies.