18864021 has 24 divisors (see below), whose sum is σ = 27906592. Its totient is φ = 11325600.

The previous prime is 18863987. The next prime is 18864023. The reversal of 18864021 is 12046881.

It is not a de Polignac number, because 18864021 - 2¹⁴ = 18847637 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18864021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18864023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56826 + ... + 57156.

Almost surely, 2^18864021 is an apocalyptic number.

18864021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18864021 is a deficient number, since it is larger than the sum of its proper divisors (9042571).

18864021 is a wasteful number, since it uses less digits than its factorization.

18864021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 513 (or 502 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 18864021 is about 4343.2730745372. The cubic root of 18864021 is about 266.2020672380.

The spelling of 18864021 in words is "eighteen million, eight hundred sixty-four thousand, twenty-one".