18390921 has 8 divisors (see below), whose sum is σ = 24686400. Its totient is φ = 12178032.

The previous prime is 18390899. The next prime is 18390929. The reversal of 18390921 is 12909381.

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

It is not a de Polignac number, because 18390921 - 2⁶ = 18390857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18390929) 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, 20125 + ... + 21018.

It is an arithmetic number, because the mean of its divisors is an integer number (3085800).

Almost surely, 2^18390921 is an apocalyptic number.

It is an amenable number.

18390921 is a deficient number, since it is larger than the sum of its proper divisors (6295479).

18390921 is a wasteful number, since it uses less digits than its factorization.

18390921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41295.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 18390921 is about 4288.4637109343. The cubic root of 18390921 is about 263.9577957098.

The spelling of 18390921 in words is "eighteen million, three hundred ninety thousand, nine hundred twenty-one".