18090021 has 8 divisors (see below), whose sum is σ = 24150880. Its totient is φ = 12044592.

The previous prime is 18090001. The next prime is 18090031. The reversal of 18090021 is 12009081.

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

It is not a de Polignac number, because 18090021 - 2⁷ = 18089893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18090021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18090001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 766 + ... + 6063.

It is an arithmetic number, because the mean of its divisors is an integer number (3018860).

Almost surely, 2^18090021 is an apocalyptic number.

It is an amenable number.

18090021 is a deficient number, since it is larger than the sum of its proper divisors (6060859).

18090021 is an equidigital number, since it uses as much as digits as its factorization.

18090021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7715.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 18090021 is about 4253.2365323363. The cubic root of 18090021 is about 262.5103052644.

The spelling of 18090021 in words is "eighteen million, ninety thousand, twenty-one".