18231138 has 24 divisors (see below), whose sum is σ = 39794508. Its totient is φ = 6031872.

The previous prime is 18231137. The next prime is 18231151. The reversal of 18231138 is 83113281.

It can be written as a sum of positive squares in 2 ways, for example, as 17867529 + 363609 = 4227^2 + 603^2 .

It is not an unprimeable number, because it can be changed into a prime (18231137) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1231 + ... + 6162.

Almost surely, 2^18231138 is an apocalyptic number.

18231138 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

18231138 is an abundant number, since it is smaller than the sum of its proper divisors (21563370).

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

18231138 is a wasteful number, since it uses less digits than its factorization.

18231138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7538 (or 7535 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 18231138 is about 4269.7936718301. The cubic root of 18231138 is about 263.1911365320.

The spelling of 18231138 in words is "eighteen million, two hundred thirty-one thousand, one hundred thirty-eight".