991579680 has 864 divisors, whose sum is σ = 4517420544. Its totient is φ = 195858432.

The previous prime is 991579663. The next prime is 991579709. The reversal of 991579680 is 86975199.

991579680 is a `hidden beast` number, since 9 + 9 + 1 + 579 + 68 + 0 = 666.

It is an unprimeable number.

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 143 ways as a sum of consecutive naturals, for example, 21097417 + ... + 21097463.

It is an arithmetic number, because the mean of its divisors is an integer number (5228496).

Almost surely, 2^991579680 is an apocalyptic number.

991579680 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 991579680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2258710272).

991579680 is an abundant number, since it is smaller than the sum of its proper divisors (3525840864).

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

991579680 is a wasteful number, since it uses less digits than its factorization.

991579680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 1224720, while the sum is 54.

The square root of 991579680 is about 31489.3582024150. The cubic root of 991579680 is about 997.1853116291.

The spelling of 991579680 in words is "nine hundred ninety-one million, five hundred seventy-nine thousand, six hundred eighty".