18311840 has 48 divisors (see below), whose sum is σ = 43559208. Its totient is φ = 7274496.

The previous prime is 18311833. The next prime is 18311857. The reversal of 18311840 is 4811381.

It can be written as a sum of positive squares in 4 ways, for example, as 13454224 + 4857616 = 3668^2 + 2204^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30584 + ... + 31176.

Almost surely, 2^18311840 is an apocalyptic number.

18311840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18311840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21779604).

18311840 is an abundant number, since it is smaller than the sum of its proper divisors (25247368).

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

18311840 is a wasteful number, since it uses less digits than its factorization.

18311840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801 (or 793 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 18311840 is about 4279.2335762377. The cubic root of 18311840 is about 263.5789124263.

The spelling of 18311840 in words is "eighteen million, three hundred eleven thousand, eight hundred forty".