18165921 has 4 divisors (see below), whose sum is σ = 24221232. Its totient is φ = 12110612.

The previous prime is 18165913. The next prime is 18165947. The reversal of 18165921 is 12956181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18165921 - 2³ = 18165913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18165991) 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, 3027651 + ... + 3027656.

It is an arithmetic number, because the mean of its divisors is an integer number (6055308).

Almost surely, 2^18165921 is an apocalyptic number.

It is an amenable number.

18165921 is a deficient number, since it is larger than the sum of its proper divisors (6055311).

18165921 is an equidigital number, since it uses as much as digits as its factorization.

18165921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6055310.

The product of its digits is 4320, while the sum is 33.

The square root of 18165921 is about 4262.1498096618. The cubic root of 18165921 is about 262.8769297009.

The spelling of 18165921 in words is "eighteen million, one hundred sixty-five thousand, nine hundred twenty-one".