18811813 has 2 divisors, whose sum is σ = 18811814. Its totient is φ = 18811812.

The previous prime is 18811789. The next prime is 18811831. The reversal of 18811813 is 31811881.

Together with next prime (18811831) 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., 14002564 + 4809249 = 3742^2 + 2193^2 .

It is an emirp because it is prime and its reverse (31811881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18811813 - 2⁹ = 18811301 is a prime.

It is equal to p_1199803 and since 18811813 and 1199803 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18811883) 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, 9405906 + 9405907.

It is an arithmetic number, because the mean of its divisors is an integer number (9405907).

Almost surely, 2^18811813 is an apocalyptic number.

It is an amenable number.

18811813 is a deficient number, since it is larger than the sum of its proper divisors (1).

18811813 is an equidigital number, since it uses as much as digits as its factorization.

18811813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1536, while the sum is 31.

The square root of 18811813 is about 4337.2586964579. The cubic root of 18811813 is about 265.9562603566.

The spelling of 18811813 in words is "eighteen million, eight hundred eleven thousand, eight hundred thirteen".