[Mithadan]

I know next to nothing about numerology or the mythical significance of numbers. Five minutes of internet research uncovered some distinction between odd and even numbers with one representing male and the other female and a similar light versus dark correlation. I cannot tie this in firmly with Tolkien's works.

However, one thing is very clear. Tolkien had a strong preference, and perhaps attached some significance, to odd numbers in specific, and possibly to prime numbers. For those who do not recall their elementary mathematics, prime numbers are divisible only by 1 and themselves. The first several primes are 1, 3, 5, 7, 11, 13, 19, etc.

Tolkien's mythos is replete with an overwhelming quantity of odd numbers, most of which are primes. What follows is a list of what I could think of off the top of my head.

Eru, the One.
The 3 Themes of the Ainulindale.
The 7 kings and 7 queens of the Valar (at least in the published Silmarillion).
The 3 Ages of the Elder days.
The 3 houses of Elves (having 4 kings, however, until Thingol tarried in Beleriand).
The 3 Noldorin princes (Feanor, Fingolfin and Finarfin).
The 7 sons of Feanor.
The 3 Silmarils.
The 3 houses of the Edain.
The 7 Fathers of the Dwarves and their corresponding houses.
The 7 Gates of Gondolin.
The 3 peaks of Thangorodrim.
The 5 children of Finarfin and 3 of Fingolfin (in the published Silmarillion at least).
7 (3, 5?) Balrogs.
The 7 rivers of Ossiriand (Gelion and its 6 tributaries).
The 5 promontories of Numenor.
7 Stones, 7 Stars and 1 White Tree.
3 peaks over Moria.
The 5 Wizards.
The 7 Gates of Minas Tirith.
The 3 Elven Towers on the Tower Hills.
The 3 groups or families of the Hobbits.
And, of course, "Three Rings for the Elven-kings under the sky, Seven for the Dwarf-lords in their halls of stone, Nine for the Mortal Men doomed to die, One for the Dark Lord on his dark throne."

Up until the Ring Verse, we have all primes, and all numbers on the above list are odd. The exception is the 9 Rings, and of course, their corresponding 9 Ringwraiths and the Nine members of the Fellowship. I wonder whether there is any significance that these are not prime numbers?

There are only two exceptions to the litany of odd and prime numbers that are of any real mythological significance in Tolkien's work, at least that I can think of. The 2 Trees and the 2 Lamps of the Valar. Again, any significance here?

Then, we have the 13 Dwarves of Thorin's Company and the intentional choice to add Bilbo as the 14th member to avoid the "unlucky" number.

No doubt, our members will be unable to resist the temptation to add to these lists, but that is not the point here. Is there any meaning to Tolkien's use of odd numbers (or primes)? Is there any significance to the exceptions; the few even numbers and the odd non-primes?