91781568 has 84 divisors (see below), whose sum is σ = 266537440. Its totient is φ = 30191616.

The previous prime is 91781563. The next prime is 91781593. The reversal of 91781568 is 86518719.

91781568 is a `hidden beast` number, since 9 + 1 + 7 + 81 + 568 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91781563) 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 in 11 ways as a sum of consecutive naturals, for example, 44496 + ... + 46512.

Almost surely, 2^91781568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91781568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133268720).

91781568 is an abundant number, since it is smaller than the sum of its proper divisors (174755872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91781568 is a wasteful number, since it uses less digits than its factorization.

91781568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2114 (or 2101 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 91781568 is about 9580.2697248042. The cubic root of 91781568 is about 451.0781850118.

The spelling of 91781568 in words is "ninety-one million, seven hundred eighty-one thousand, five hundred sixty-eight".