18381664 has 72 divisors (see below), whose sum is σ = 44384760. Its totient is φ = 7451136.

The previous prime is 18381647. The next prime is 18381677. The reversal of 18381664 is 46618381.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29484 + ... + 30100.

It is an arithmetic number, because the mean of its divisors is an integer number (616455).

Almost surely, 2^18381664 is an apocalyptic number.

18381664 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18381664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22192380).

18381664 is an abundant number, since it is smaller than the sum of its proper divisors (26003096).

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

18381664 is a wasteful number, since it uses less digits than its factorization.

18381664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660 (or 645 counting only the distinct ones).

The product of its digits is 27648, while the sum is 37.

The square root of 18381664 is about 4287.3842841528. The cubic root of 18381664 is about 263.9135008935.

The spelling of 18381664 in words is "eighteen million, three hundred eighty-one thousand, six hundred sixty-four".