18221339 has 2 divisors, whose sum is σ = 18221340. Its totient is φ = 18221338.

The previous prime is 18221257. The next prime is 18221341. The reversal of 18221339 is 93312281.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18221339 - 2²⁰ = 17172763 is a prime.

Together with 18221341, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1164494 and since 18221339 and 1164494 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (18221389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9110669 + 9110670.

It is an arithmetic number, because the mean of its divisors is an integer number (9110670).

Almost surely, 2^18221339 is an apocalyptic number.

18221339 is a deficient number, since it is larger than the sum of its proper divisors (1).

18221339 is an equidigital number, since it uses as much as digits as its factorization.

18221339 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 29.

The square root of 18221339 is about 4268.6460382655. The cubic root of 18221339 is about 263.1439741415.

The spelling of 18221339 in words is "eighteen million, two hundred twenty-one thousand, three hundred thirty-nine".