18088991 has 4 divisors (see below), whose sum is σ = 18231552. Its totient is φ = 17946432.

The previous prime is 18088981. The next prime is 18088997. The reversal of 18088991 is 19988081.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18088991 - 2²² = 13894687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18088997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71090 + ... + 71343.

It is an arithmetic number, because the mean of its divisors is an integer number (4557888).

Almost surely, 2^18088991 is an apocalyptic number.

18088991 is a deficient number, since it is larger than the sum of its proper divisors (142561).

18088991 is a wasteful number, since it uses less digits than its factorization.

18088991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142560.

The product of its (nonzero) digits is 41472, while the sum is 44.

The square root of 18088991 is about 4253.1154463522. The cubic root of 18088991 is about 262.5053229457.

The spelling of 18088991 in words is "eighteen million, eighty-eight thousand, nine hundred ninety-one".