91809439 has 2 divisors, whose sum is σ = 91809440. Its totient is φ = 91809438.

The previous prime is 91809437. The next prime is 91809467. The reversal of 91809439 is 93490819.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91809439 - 2¹ = 91809437 is a prime.

Together with 91809437, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 91809395 and 91809404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91809437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45904719 + 45904720.

It is an arithmetic number, because the mean of its divisors is an integer number (45904720).

Almost surely, 2^91809439 is an apocalyptic number.

91809439 is a deficient number, since it is larger than the sum of its proper divisors (1).

91809439 is an equidigital number, since it uses as much as digits as its factorization.

91809439 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 91809439 is about 9581.7242185319. The cubic root of 91809439 is about 451.1238395226.

The spelling of 91809439 in words is "ninety-one million, eight hundred nine thousand, four hundred thirty-nine".