91000008 has 96 divisors (see below), whose sum is σ = 272095200. Its totient is φ = 27244800.

The previous prime is 90999989. The next prime is 91000009. The reversal of 91000008 is 80000019.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (91000009) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 69843 + ... + 71133.

It is an arithmetic number, because the mean of its divisors is an integer number (2834325).

Almost surely, 2^91000008 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 91000008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136047600).

91000008 is an abundant number, since it is smaller than the sum of its proper divisors (181095192).

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

91000008 is a wasteful number, since it uses less digits than its factorization.

91000008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1403 (or 1396 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 91000008 is about 9539.3924334834. The cubic root of 91000008 is about 449.7941577083.

The spelling of 91000008 in words is "ninety-one million, eight", and thus it is an aban number and an uban number.