991568 has 20 divisors (see below), whose sum is σ = 1988340. Its totient is φ = 478464.

The previous prime is 991567. The next prime is 991579. The reversal of 991568 is 865199.

It can be written as a sum of positive squares in 2 ways, for example, as 238144 + 753424 = 488^2 + 868^2 .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991568.

It is not an unprimeable number, because it can be changed into a prime (991567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 605 + ... + 1532.

It is an arithmetic number, because the mean of its divisors is an integer number (99417).

2⁹⁹¹⁵⁶⁸ is an apocalyptic number.

It is an amenable number.

991568 is an abundant number, since it is smaller than the sum of its proper divisors (996772).

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

991568 is a wasteful number, since it uses less digits than its factorization.

991568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2174 (or 2168 counting only the distinct ones).

The product of its digits is 19440, while the sum is 38.

The square root of 991568 is about 995.7750750044. The cubic root of 991568 is about 99.7181396271.

The spelling of 991568 in words is "nine hundred ninety-one thousand, five hundred sixty-eight".