9991680 has 80 divisors (see below), whose sum is σ = 31966704. Its totient is φ = 2662400.

The previous prime is 9991673. The next prime is 9991691. The reversal of 9991680 is 861999.

It is a tau number, because it is divible by the number of its divisors (80).

It is a nialpdrome in base 16.

It is a congruent number.

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, 7030 + ... + 8330.

Almost surely, 2^9991680 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 9991680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15983352).

9991680 is an abundant number, since it is smaller than the sum of its proper divisors (21975024).

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

9991680 is a wasteful number, since it uses less digits than its factorization.

9991680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1327 (or 1311 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 42.

The square root of 9991680 is about 3160.9618789223. The cubic root of 9991680 is about 215.3837027696.

The spelling of 9991680 in words is "nine million, nine hundred ninety-one thousand, six hundred eighty".