18909438 has 8 divisors (see below), whose sum is σ = 37818888. Its totient is φ = 6303144.

The previous prime is 18909431. The next prime is 18909469. The reversal of 18909438 is 83490981.

It is a sphenic number, since it is the product of 3 distinct primes.

18909438 is an admirable number.

It is an alternating number because its digits alternate between odd and even.

It is a self number, because there is not a number n which added to its sum of digits gives 18909438.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18909431) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1575781 + ... + 1575792.

It is an arithmetic number, because the mean of its divisors is an integer number (4727361).

Almost surely, 2^18909438 is an apocalyptic number.

18909438 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

18909438 is a wasteful number, since it uses less digits than its factorization.

18909438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3151578.

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 18909438 is about 4348.4983615037. The cubic root of 18909438 is about 266.4155319696.

The spelling of 18909438 in words is "eighteen million, nine hundred nine thousand, four hundred thirty-eight".