Those numbers are factors of secp256k1 modified order

n    = 115792089237316195423570985008687907852837564279074904382605163141518161494337 (prime number)
n-1 = 115792089237316195423570985008687907852837564279074904382605163141518161494336 (composite number)

factorisation of n-1 into primes: 2*2*2*2*2*2 * 3 * 149 * 631 * 107361793816595537 * 174723607534414371449 * 341948486974166000522343609283189

18051648 = 2*2*2*2*2*2 * 3 * 149 * 631
9025824   = 2*2*2*2*2 * 3 * 149 * 631
6017216   = 2*2*2*2*2*2 * 149 * 631

and so on

I don't see any special magic here. In fact, BTC's real private key can be divisible by any prime number and also can be prime by itself. Due to the fact that secp256k1 is a cyclic group, we cannot check whether the result of dividing an unknown number (public key) is an integer or a fraction (in real math, outside of cyclic group), so we cannot make any meaningful conclusions from the results obtained.