18131808 has 48 divisors (see below), whose sum is σ = 48323520. Its totient is φ = 5951616.

The previous prime is 18131803. The next prime is 18131819. The reversal of 18131808 is 80813181.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×18131808² = 657524922697728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18131803) 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, 5023 + ... + 7841.

It is an arithmetic number, because the mean of its divisors is an integer number (1006740).

Almost surely, 2^18131808 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 18131808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24161760).

18131808 is an abundant number, since it is smaller than the sum of its proper divisors (30191712).

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

18131808 is a wasteful number, since it uses less digits than its factorization.

18131808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2899 (or 2891 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 30.

The square root of 18131808 is about 4258.1460754652. The cubic root of 18131808 is about 262.7122781755.

Adding to 18131808 its reverse (80813181), we get a palindrome (98944989).

The spelling of 18131808 in words is "eighteen million, one hundred thirty-one thousand, eight hundred eight".