18356321 has 2 divisors, whose sum is σ = 18356322. Its totient is φ = 18356320.

The previous prime is 18356297. The next prime is 18356341. The reversal of 18356321 is 12365381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12285025 + 6071296 = 3505^2 + 2464^2 .

It is a cyclic number.

It is not a de Polignac number, because 18356321 - 2¹⁸ = 18094177 is a prime.

It is a Chen prime.

It is equal to p_1172639 and since 18356321 and 1172639 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 (18356341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9178160 + 9178161.

It is an arithmetic number, because the mean of its divisors is an integer number (9178161).

Almost surely, 2^18356321 is an apocalyptic number.

It is an amenable number.

18356321 is a deficient number, since it is larger than the sum of its proper divisors (1).

18356321 is an equidigital number, since it uses as much as digits as its factorization.

18356321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 29.

The square root of 18356321 is about 4284.4277330817. The cubic root of 18356321 is about 263.7921583067.

The spelling of 18356321 in words is "eighteen million, three hundred fifty-six thousand, three hundred twenty-one".