18909864 has 96 divisors (see below), whose sum is σ = 56347200. Its totient is φ = 5702400.

The previous prime is 18909853. The next prime is 18909901. The reversal of 18909864 is 46890981.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31164 + ... + 31764.

It is an arithmetic number, because the mean of its divisors is an integer number (586950).

Almost surely, 2^18909864 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 18909864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28173600).

18909864 is an abundant number, since it is smaller than the sum of its proper divisors (37437336).

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

18909864 is a wasteful number, since it uses less digits than its factorization.

18909864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 655 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 18909864 is about 4348.5473436540. The cubic root of 18909864 is about 266.4175325961.

The spelling of 18909864 in words is "eighteen million, nine hundred nine thousand, eight hundred sixty-four".