18918438 has 32 divisors (see below), whose sum is σ = 47174400. Its totient is φ = 4913760.

The previous prime is 18918437. The next prime is 18918451. The reversal of 18918438 is 83481981.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 18918438.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18918437) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20013 + ... + 20936.

It is an arithmetic number, because the mean of its divisors is an integer number (1474200).

Almost surely, 2^18918438 is an apocalyptic number.

18918438 is an abundant number, since it is smaller than the sum of its proper divisors (28255962).

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

18918438 is a wasteful number, since it uses less digits than its factorization.

18918438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40972.

The product of its digits is 55296, while the sum is 42.

The square root of 18918438 is about 4349.5330783890. The cubic root of 18918438 is about 266.4577923387.

The spelling of 18918438 in words is "eighteen million, nine hundred eighteen thousand, four hundred thirty-eight".