18909440 has 144 divisors (see below), whose sum is σ = 52980480. Its totient is φ = 6389760.

The previous prime is 18909431. The next prime is 18909469. The reversal of 18909440 is 4490981.

It is a super-2 number, since 2×18909440² = 715133842227200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18909440.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 239321 + ... + 239399.

It is an arithmetic number, because the mean of its divisors is an integer number (367920).

Almost surely, 2^18909440 is an apocalyptic number.

18909440 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 18909440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26490240).

18909440 is an abundant number, since it is smaller than the sum of its proper divisors (34071040).

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

18909440 is a wasteful number, since it uses less digits than its factorization.

18909440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 18909440 is about 4348.4985914681. The cubic root of 18909440 is about 266.4155413623.

The spelling of 18909440 in words is "eighteen million, nine hundred nine thousand, four hundred forty".