18320640 has 144 divisors (see below), whose sum is σ = 63184128. Its totient is φ = 4497408.

The previous prime is 18320633. The next prime is 18320651. The reversal of 18320640 is 4602381.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 18320640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49737 + ... + 50103.

Almost surely, 2^18320640 is an apocalyptic number.

18320640 is a gapful number since it is divisible by the number (10) 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 18320640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31592064).

18320640 is an abundant number, since it is smaller than the sum of its proper divisors (44863488).

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

18320640 is a wasteful number, since it uses less digits than its factorization.

18320640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404 (or 390 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 18320640 is about 4280.2616742438. The cubic root of 18320640 is about 263.6211277903.

The spelling of 18320640 in words is "eighteen million, three hundred twenty thousand, six hundred forty".