91810813 has 2 divisors, whose sum is σ = 91810814. Its totient is φ = 91810812.

The previous prime is 91810769. The next prime is 91810841. The reversal of 91810813 is 31801819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47361924 + 44448889 = 6882^2 + 6667^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91810813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91810853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45905406 + 45905407.

It is an arithmetic number, because the mean of its divisors is an integer number (45905407).

Almost surely, 2^91810813 is an apocalyptic number.

It is an amenable number.

91810813 is a deficient number, since it is larger than the sum of its proper divisors (1).

91810813 is an equidigital number, since it uses as much as digits as its factorization.

91810813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 31.

The square root of 91810813 is about 9581.7959172589. The cubic root of 91810813 is about 451.1260899849.

The spelling of 91810813 in words is "ninety-one million, eight hundred ten thousand, eight hundred thirteen".