18031904 has 36 divisors (see below), whose sum is σ = 39029382. Its totient is φ = 8194560.

The previous prime is 18031903. The next prime is 18031907. The reversal of 18031904 is 40913081.

It can be written as a sum of positive squares in only one way, i.e., 17472400 + 559504 = 4180^2 + 748^2 .

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (18031903) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1544 + ... + 6200.

Almost surely, 2^18031904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18031904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19514691).

18031904 is an abundant number, since it is smaller than the sum of its proper divisors (20997478).

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

18031904 is a wasteful number, since it uses less digits than its factorization.

18031904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4689 (or 4670 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 18031904 is about 4246.3989449886. The cubic root of 18031904 is about 262.2288853149.

Adding to 18031904 its reverse (40913081), we get a palindrome (58944985).

The spelling of 18031904 in words is "eighteen million, thirty-one thousand, nine hundred four".