18099991 has 8 divisors (see below), whose sum is σ = 22277024. Its totient is φ = 14320800.

The previous prime is 18099971. The next prime is 18099997. The reversal of 18099991 is 19999081.

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

It is not a de Polignac number, because 18099991 - 2⁹ = 18099479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18099997) 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, 99360 + ... + 99541.

It is an arithmetic number, because the mean of its divisors is an integer number (2784628).

Almost surely, 2^18099991 is an apocalyptic number.

18099991 is a deficient number, since it is larger than the sum of its proper divisors (4177033).

18099991 is a wasteful number, since it uses less digits than its factorization.

18099991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198921.

The product of its (nonzero) digits is 52488, while the sum is 46.

The square root of 18099991 is about 4254.4084195103. The cubic root of 18099991 is about 262.5585224016.

The spelling of 18099991 in words is "eighteen million, ninety-nine thousand, nine hundred ninety-one".