18685213 has 2 divisors, whose sum is σ = 18685214. Its totient is φ = 18685212.

The previous prime is 18685187. The next prime is 18685231. The reversal of 18685213 is 31258681.

Together with next prime (18685231) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10517049 + 8168164 = 3243^2 + 2858^2 .

It is an emirp because it is prime and its reverse (31258681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18685213 - 2⁵ = 18685181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18685313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9342606 + 9342607.

It is an arithmetic number, because the mean of its divisors is an integer number (9342607).

Almost surely, 2^18685213 is an apocalyptic number.

It is an amenable number.

18685213 is a deficient number, since it is larger than the sum of its proper divisors (1).

18685213 is an equidigital number, since it uses as much as digits as its factorization.

18685213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 18685213 is about 4322.6395871042. The cubic root of 18685213 is about 265.3583049245.

The spelling of 18685213 in words is "eighteen million, six hundred eighty-five thousand, two hundred thirteen".