991680 has 56 divisors (see below), whose sum is σ = 3151632. Its totient is φ = 264192.

The previous prime is 991663. The next prime is 991693. The reversal of 991680 is 86199.

It is a happy number.

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 991680.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 444 + ... + 1476.

2⁹⁹¹⁶⁸⁰ 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 991680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1575816).

991680 is an abundant number, since it is smaller than the sum of its proper divisors (2159952).

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

991680 is a wasteful number, since it uses less digits than its factorization.

991680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053 (or 1043 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 991680 is about 995.8313110161. The cubic root of 991680 is about 99.7218939539.

The spelling of 991680 in words is "nine hundred ninety-one thousand, six hundred eighty".