91931809 has 2 divisors, whose sum is σ = 91931810. Its totient is φ = 91931808.

The previous prime is 91931797. The next prime is 91931813. The reversal of 91931809 is 90813919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66781584 + 25150225 = 8172^2 + 5015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91931809 is a prime.

It is a super-3 number, since 3×91931809³ (a number of 25 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91931849) 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, 45965904 + 45965905.

It is an arithmetic number, because the mean of its divisors is an integer number (45965905).

Almost surely, 2^91931809 is an apocalyptic number.

It is an amenable number.

91931809 is a deficient number, since it is larger than the sum of its proper divisors (1).

91931809 is an equidigital number, since it uses as much as digits as its factorization.

91931809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 40.

The square root of 91931809 is about 9588.1076860870. The cubic root of 91931809 is about 451.3241802733.

The spelling of 91931809 in words is "ninety-one million, nine hundred thirty-one thousand, eight hundred nine".