91665728 has 168 divisors, whose sum is σ = 243230400. Its totient is φ = 33454080.

The previous prime is 91665727. The next prime is 91665767. The reversal of 91665728 is 82756619.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91665727) 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 23 ways as a sum of consecutive naturals, for example, 1029908 + ... + 1029996.

It is an arithmetic number, because the mean of its divisors is an integer number (1447800).

Almost surely, 2^91665728 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 91665728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121615200).

91665728 is an abundant number, since it is smaller than the sum of its proper divisors (151564672).

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

91665728 is a wasteful number, since it uses less digits than its factorization.

91665728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 128 counting only the distinct ones).

The product of its digits is 181440, while the sum is 44.

The square root of 91665728 is about 9574.2220571700. Note that the first 3 decimals coincide. The cubic root of 91665728 is about 450.8883324565. Note that the first 3 decimals are identical.

The spelling of 91665728 in words is "ninety-one million, six hundred sixty-five thousand, seven hundred twenty-eight".