18531864 has 72 divisors (see below), whose sum is σ = 54383940. Its totient is φ = 5698368.

The previous prime is 18531829. The next prime is 18531881. The reversal of 18531864 is 46813581.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11407 + ... + 12929.

Almost surely, 2^18531864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18531864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27191970).

18531864 is an abundant number, since it is smaller than the sum of its proper divisors (35852076).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18531864 is a wasteful number, since it uses less digits than its factorization.

18531864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1561 (or 1541 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 18531864 is about 4304.8651546825. The cubic root of 18531864 is about 264.6303806280.

The spelling of 18531864 in words is "eighteen million, five hundred thirty-one thousand, eight hundred sixty-four".