18221839 has 4 divisors (see below), whose sum is σ = 18242224. Its totient is φ = 18201456.

The previous prime is 18221837. The next prime is 18221851. The reversal of 18221839 is 93812281.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18221839 - 2¹ = 18221837 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 (18221837) 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 3 ways as a sum of consecutive naturals, for example, 8787 + ... + 10660.

It is an arithmetic number, because the mean of its divisors is an integer number (4560556).

Almost surely, 2^18221839 is an apocalyptic number.

18221839 is a deficient number, since it is larger than the sum of its proper divisors (20385).

18221839 is an equidigital number, since it uses as much as digits as its factorization.

18221839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20384.

The product of its digits is 6912, while the sum is 34.

The square root of 18221839 is about 4268.7046044438. The cubic root of 18221839 is about 263.1463810408.

The spelling of 18221839 in words is "eighteen million, two hundred twenty-one thousand, eight hundred thirty-nine".