991564704 has 288 divisors, whose sum is σ = 3269185920. Its totient is φ = 282507264.

The previous prime is 991564681. The next prime is 991564709. The reversal of 991564704 is 407465199.

It is a tau number, because it is divible by the number of its divisors (288).

It is a self number, because there is not a number n which added to its sum of digits gives 991564704.

It is not an unprimeable number, because it can be changed into a prime (991564709) 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 47 ways as a sum of consecutive naturals, for example, 3770077 + ... + 3770339.

It is an arithmetic number, because the mean of its divisors is an integer number (11351340).

Almost surely, 2^991564704 is an apocalyptic number.

991564704 is the 16832-nd nonagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991564704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1634592960).

991564704 is an abundant number, since it is smaller than the sum of its proper divisors (2277621216).

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

991564704 is a wasteful number, since it uses less digits than its factorization.

991564704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364 (or 353 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The square root of 991564704 is about 31489.1204068961. The cubic root of 991564704 is about 997.1802913829.

The spelling of 991564704 in words is "nine hundred ninety-one million, five hundred sixty-four thousand, seven hundred four".