991165824 has 384 divisors, whose sum is σ = 3402622080. Its totient is φ = 273530880.

The previous prime is 991165801. The next prime is 991165873. The reversal of 991165824 is 428561199.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 991165824.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9263179 + ... + 9263285.

It is an arithmetic number, because the mean of its divisors is an integer number (8860995).

Almost surely, 2^991165824 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 991165824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1701311040).

991165824 is an abundant number, since it is smaller than the sum of its proper divisors (2411456256).

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

991165824 is a wasteful number, since it uses less digits than its factorization.

991165824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 183 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 991165824 is about 31482.7861537063. The cubic root of 991165824 is about 997.0465604489.

The spelling of 991165824 in words is "nine hundred ninety-one million, one hundred sixty-five thousand, eight hundred twenty-four".