18939138 has 16 divisors (see below), whose sum is σ = 37920960. Its totient is φ = 6305936.

The previous prime is 18939131. The next prime is 18939157. The reversal of 18939138 is 83193981.

It is a happy number.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18939138.

It is not an unprimeable number, because it can be changed into a prime (18939131) 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, 9331 + ... + 11177.

It is an arithmetic number, because the mean of its divisors is an integer number (2370060).

Almost surely, 2^18939138 is an apocalyptic number.

18939138 is an abundant number, since it is smaller than the sum of its proper divisors (18981822).

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

18939138 is a wasteful number, since it uses less digits than its factorization.

18939138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3561.

The product of its digits is 46656, while the sum is 42.

The square root of 18939138 is about 4351.9119935955. The cubic root of 18939138 is about 266.5549403489.

The spelling of 18939138 in words is "eighteen million, nine hundred thirty-nine thousand, one hundred thirty-eight".