18438390 has 24 divisors (see below), whose sum is σ = 47940048. Its totient is φ = 4916880.

The previous prime is 18438383. The next prime is 18438391. The reversal of 18438390 is 9383481.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18438391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102346 + ... + 102525.

It is an arithmetic number, because the mean of its divisors is an integer number (1997502).

Almost surely, 2^18438390 is an apocalyptic number.

18438390 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18438390 is an abundant number, since it is smaller than the sum of its proper divisors (29501658).

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

18438390 is a wasteful number, since it uses less digits than its factorization.

18438390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204884 (or 204881 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 18438390 is about 4293.9946436855. The cubic root of 18438390 is about 264.1847020142.

The spelling of 18438390 in words is "eighteen million, four hundred thirty-eight thousand, three hundred ninety".