18138444 has 24 divisors (see below), whose sum is σ = 44163840. Its totient is φ = 5783184.

The previous prime is 18138443. The next prime is 18138451. The reversal of 18138444 is 44483181.

It is a super-2 number, since 2×18138444² = 658006301482272, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18138443) 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, 32584 + ... + 33135.

It is an arithmetic number, because the mean of its divisors is an integer number (1840160).

Almost surely, 2^18138444 is an apocalyptic number.

It is an amenable number.

18138444 is an abundant number, since it is smaller than the sum of its proper divisors (26025396).

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

18138444 is a wasteful number, since it uses less digits than its factorization.

18138444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65749 (or 65747 counting only the distinct ones).

The product of its digits is 12288, while the sum is 33.

The square root of 18138444 is about 4258.9252165306. The cubic root of 18138444 is about 262.7443239968.

The spelling of 18138444 in words is "eighteen million, one hundred thirty-eight thousand, four hundred forty-four".