18087891 has 8 divisors (see below), whose sum is σ = 24244224. Its totient is φ = 11995080.

The previous prime is 18087887. The next prime is 18087899. The reversal of 18087891 is 19878081.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18087891 - 2² = 18087887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18087899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15211 + ... + 16356.

It is an arithmetic number, because the mean of its divisors is an integer number (3030528).

Almost surely, 2^18087891 is an apocalyptic number.

18087891 is a deficient number, since it is larger than the sum of its proper divisors (6156333).

18087891 is a wasteful number, since it uses less digits than its factorization.

18087891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31761.

The product of its (nonzero) digits is 32256, while the sum is 42.

The square root of 18087891 is about 4252.9861274168. The cubic root of 18087891 is about 262.5000018141.

The spelling of 18087891 in words is "eighteen million, eighty-seven thousand, eight hundred ninety-one".