991258560 has 280 divisors, whose sum is σ = 3562685280. Its totient is φ = 261605376.

The previous prime is 991258549. The next prime is 991258589. The reversal of 991258560 is 65852199.

991258560 is a `hidden beast` number, since 9 + 9 + 1 + 2 + 585 + 60 = 666.

991258560 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 4328526 + ... + 4328754.

It is an arithmetic number, because the mean of its divisors is an integer number (12723876).

Almost surely, 2^991258560 is an apocalyptic number.

991258560 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991258560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1781342640).

991258560 is an abundant number, since it is smaller than the sum of its proper divisors (2571426720).

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

991258560 is a wasteful number, since it uses less digits than its factorization.

991258560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The square root of 991258560 is about 31484.2589241036. The cubic root of 991258560 is about 997.0776548847.

The spelling of 991258560 in words is "nine hundred ninety-one million, two hundred fifty-eight thousand, five hundred sixty".