18643921 has 8 divisors (see below), whose sum is σ = 19875200. Its totient is φ = 17437680.

The previous prime is 18643909. The next prime is 18643939. The reversal of 18643921 is 12934681.

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 18643921 - 2²¹ = 16546769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18643901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4710 + ... + 7711.

It is an arithmetic number, because the mean of its divisors is an integer number (2484400).

Almost surely, 2^18643921 is an apocalyptic number.

It is an amenable number.

18643921 is a deficient number, since it is larger than the sum of its proper divisors (1231279).

18643921 is a wasteful number, since it uses less digits than its factorization.

18643921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12519.

The product of its digits is 10368, while the sum is 34.

The square root of 18643921 is about 4317.8606971508. The cubic root of 18643921 is about 265.1626911276.

The spelling of 18643921 in words is "eighteen million, six hundred forty-three thousand, nine hundred twenty-one".