18806813 has 2 divisors, whose sum is σ = 18806814. Its totient is φ = 18806812.

The previous prime is 18806797. The next prime is 18806831. The reversal of 18806813 is 31860881.

It is a happy number.

Together with next prime (18806831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13227769 + 5579044 = 3637^2 + 2362^2 .

It is a cyclic number.

It is not a de Polignac number, because 18806813 - 2⁴ = 18806797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18826813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9403406 + 9403407.

It is an arithmetic number, because the mean of its divisors is an integer number (9403407).

Almost surely, 2^18806813 is an apocalyptic number.

It is an amenable number.

18806813 is a deficient number, since it is larger than the sum of its proper divisors (1).

18806813 is an equidigital number, since it uses as much as digits as its factorization.

18806813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 18806813 is about 4336.6822572100. The cubic root of 18806813 is about 265.9326953918.

The spelling of 18806813 in words is "eighteen million, eight hundred six thousand, eight hundred thirteen".