18938021 has 8 divisors (see below), whose sum is σ = 19166400. Its totient is φ = 18711360.

The previous prime is 18938011. The next prime is 18938047. The reversal of 18938021 is 12083981.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18938021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18938011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42920 + ... + 43358.

It is an arithmetic number, because the mean of its divisors is an integer number (2395800).

Almost surely, 2^18938021 is an apocalyptic number.

It is an amenable number.

18938021 is a deficient number, since it is larger than the sum of its proper divisors (228379).

18938021 is a wasteful number, since it uses less digits than its factorization.

18938021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 859.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 18938021 is about 4351.7836573065. The cubic root of 18938021 is about 266.5496999182.

The spelling of 18938021 in words is "eighteen million, nine hundred thirty-eight thousand, twenty-one".