91989565 has 12 divisors (see below), whose sum is σ = 111257172. Its totient is φ = 73015040.

The previous prime is 91989497. The next prime is 91989577. The reversal of 91989565 is 56598919.

It can be written as a sum of positive squares in 6 ways, for example, as 232324 + 91757241 = 482^2 + 9579^2 .

It is not a de Polignac number, because 91989565 - 2¹¹ = 91987517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 327225 + ... + 327505.

It is an arithmetic number, because the mean of its divisors is an integer number (9271431).

Almost surely, 2^91989565 is an apocalyptic number.

It is an amenable number.

91989565 is a deficient number, since it is larger than the sum of its proper divisors (19267607).

91989565 is an equidigital number, since it uses as much as digits as its factorization.

91989565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 800 (or 519 counting only the distinct ones).

The product of its digits is 874800, while the sum is 52.

The square root of 91989565 is about 9591.1190692223. The cubic root of 91989565 is about 451.4186750326.

The spelling of 91989565 in words is "ninety-one million, nine hundred eighty-nine thousand, five hundred sixty-five".