18521808 has 80 divisors (see below), whose sum is σ = 52615680. Its totient is φ = 5588352.

The previous prime is 18521801. The next prime is 18521809. The reversal of 18521808 is 80812581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18521801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20535 + ... + 21417.

It is an arithmetic number, because the mean of its divisors is an integer number (657696).

Almost surely, 2^18521808 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 18521808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26307840).

18521808 is an abundant number, since it is smaller than the sum of its proper divisors (34093872).

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

18521808 is a wasteful number, since it uses less digits than its factorization.

18521808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 936 (or 930 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 33.

The square root of 18521808 is about 4303.6970153578. The cubic root of 18521808 is about 264.5825062463.

The spelling of 18521808 in words is "eighteen million, five hundred twenty-one thousand, eight hundred eight".