18868021 has 2 divisors, whose sum is σ = 18868022. Its totient is φ = 18868020.

The previous prime is 18868001. The next prime is 18868043. The reversal of 18868021 is 12086881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15295921 + 3572100 = 3911^2 + 1890^2 .

It is a cyclic number.

It is not a de Polignac number, because 18868021 - 2¹³ = 18859829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18868001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9434010 + 9434011.

It is an arithmetic number, because the mean of its divisors is an integer number (9434011).

Almost surely, 2^18868021 is an apocalyptic number.

It is an amenable number.

18868021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18868021 is an equidigital number, since it uses as much as digits as its factorization.

18868021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 18868021 is about 4343.7335323429. The cubic root of 18868021 is about 266.2208814137.

The spelling of 18868021 in words is "eighteen million, eight hundred sixty-eight thousand, twenty-one".