91785565 has 4 divisors (see below), whose sum is σ = 110142684. Its totient is φ = 73428448.

The previous prime is 91785553. The next prime is 91785569. The reversal of 91785565 is 56558719.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50851161 + 40934404 = 7131^2 + 6398^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91785565 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91785569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9178552 + ... + 9178561.

It is an arithmetic number, because the mean of its divisors is an integer number (27535671).

Almost surely, 2^91785565 is an apocalyptic number.

It is an amenable number.

91785565 is a deficient number, since it is larger than the sum of its proper divisors (18357119).

91785565 is a wasteful number, since it uses less digits than its factorization.

91785565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18357118.

The product of its digits is 378000, while the sum is 46.

The square root of 91785565 is about 9580.4783283508. The cubic root of 91785565 is about 451.0847329254.

The spelling of 91785565 in words is "ninety-one million, seven hundred eighty-five thousand, five hundred sixty-five".