18138438 has 16 divisors (see below), whose sum is σ = 40307760. Its totient is φ = 6046128.

The previous prime is 18138437. The next prime is 18138443. The reversal of 18138438 is 83483181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18138437) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 167895 + ... + 168002.

It is an arithmetic number, because the mean of its divisors is an integer number (2519235).

Almost surely, 2^18138438 is an apocalyptic number.

18138438 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

18138438 is an abundant number, since it is smaller than the sum of its proper divisors (22169322).

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

18138438 is a wasteful number, since it uses less digits than its factorization.

18138438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335908 (or 335902 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 18138438 is about 4258.9245121274. The cubic root of 18138438 is about 262.7442950258.

The spelling of 18138438 in words is "eighteen million, one hundred thirty-eight thousand, four hundred thirty-eight".