18921321 has 12 divisors (see below), whose sum is σ = 28769520. Its totient is φ = 11950200.

The previous prime is 18921317. The next prime is 18921337. The reversal of 18921321 is 12312981.

It is not a de Polignac number, because 18921321 - 2² = 18921317 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18925321) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55155 + ... + 55496.

It is an arithmetic number, because the mean of its divisors is an integer number (2397460).

Almost surely, 2^18921321 is an apocalyptic number.

It is an amenable number.

18921321 is a deficient number, since it is larger than the sum of its proper divisors (9848199).

18921321 is a wasteful number, since it uses less digits than its factorization.

18921321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110676 (or 110673 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 18921321 is about 4349.8644806476. The cubic root of 18921321 is about 266.4713269091.

The spelling of 18921321 in words is "eighteen million, nine hundred twenty-one thousand, three hundred twenty-one".