18236021 has 8 divisors (see below), whose sum is σ = 18806424. Its totient is φ = 17671680.

The previous prime is 18236017. The next prime is 18236063. The reversal of 18236021 is 12063281.

It can be written as a sum of positive squares in 4 ways, for example, as 45796 + 18190225 = 214^2 + 4265^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 18236021 - 2² = 18236017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18236221) 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, 5021 + ... + 7853.

It is an arithmetic number, because the mean of its divisors is an integer number (2350803).

Almost surely, 2^18236021 is an apocalyptic number.

It is an amenable number.

18236021 is a deficient number, since it is larger than the sum of its proper divisors (570403).

18236021 is a wasteful number, since it uses less digits than its factorization.

18236021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3031.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 18236021 is about 4270.3654410366. The cubic root of 18236021 is about 263.2146320044.

The spelling of 18236021 in words is "eighteen million, two hundred thirty-six thousand, twenty-one".