991742688 has 72 divisors (see below), whose sum is σ = 2825510688. Its totient is φ = 329966592.

The previous prime is 991742683. The next prime is 991742707. The reversal of 991742688 is 886247199.

991742688 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991742683) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 167881 + ... + 173687.

It is an arithmetic number, because the mean of its divisors is an integer number (39243204).

Almost surely, 2^991742688 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 991742688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1412755344).

991742688 is an abundant number, since it is smaller than the sum of its proper divisors (1833768000).

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

991742688 is a wasteful number, since it uses less digits than its factorization.

991742688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6416 (or 6405 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 54.

The square root of 991742688 is about 31491.9463990399. The cubic root of 991742688 is about 997.2399518092.

The spelling of 991742688 in words is "nine hundred ninety-one million, seven hundred forty-two thousand, six hundred eighty-eight".