18138393 has 24 divisors (see below), whose sum is σ = 32247488. Its totient is φ = 9567072.

The previous prime is 18138361. The next prime is 18138397. The reversal of 18138393 is 39383181.

It is not a de Polignac number, because 18138393 - 2⁵ = 18138361 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18138397) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10255 + ... + 11892.

Almost surely, 2^18138393 is an apocalyptic number.

18138393 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18138393 is a deficient number, since it is larger than the sum of its proper divisors (14109095).

18138393 is a wasteful number, since it uses less digits than its factorization.

18138393 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22173 (or 22170 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 18138393 is about 4258.9192291003. The cubic root of 18138393 is about 262.7440777432.

It can be divided in two parts, 181383 and 93, that added together give a square (181476 = 426²).

The spelling of 18138393 in words is "eighteen million, one hundred thirty-eight thousand, three hundred ninety-three".