91989768 has 64 divisors (see below), whose sum is σ = 252383040. Its totient is φ = 27765504.

The previous prime is 91989767. The next prime is 91989841. The reversal of 91989768 is 86798919.

It is not an unprimeable number, because it can be changed into a prime (91989767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13755 + ... + 19317.

It is an arithmetic number, because the mean of its divisors is an integer number (3943485).

Almost surely, 2^91989768 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 91989768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126191520).

91989768 is an abundant number, since it is smaller than the sum of its proper divisors (160393272).

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

91989768 is a wasteful number, since it uses less digits than its factorization.

91989768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5638 (or 5634 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 57.

The square root of 91989768 is about 9591.1296519232. The cubic root of 91989768 is about 451.4190070917.

The spelling of 91989768 in words is "ninety-one million, nine hundred eighty-nine thousand, seven hundred sixty-eight".