91806809 has 2 divisors, whose sum is σ = 91806810. Its totient is φ = 91806808.

The previous prime is 91806791. The next prime is 91806821. The reversal of 91806809 is 90860819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 89718784 + 2088025 = 9472^2 + 1445^2 .

It is a cyclic number.

It is not a de Polignac number, because 91806809 - 2²⁰ = 90758233 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91806899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45903404 + 45903405.

It is an arithmetic number, because the mean of its divisors is an integer number (45903405).

Almost surely, 2^91806809 is an apocalyptic number.

It is an amenable number.

91806809 is a deficient number, since it is larger than the sum of its proper divisors (1).

91806809 is an equidigital number, since it uses as much as digits as its factorization.

91806809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 91806809 is about 9581.5869771140. The cubic root of 91806809 is about 451.1195318063.

The spelling of 91806809 in words is "ninety-one million, eight hundred six thousand, eight hundred nine".