991931776 has 128 divisors (see below), whose sum is σ = 2362932000. Its totient is φ = 409436160.

The previous prime is 991931767. The next prime is 991931791. The reversal of 991931776 is 677139199.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 693430 + ... + 694858.

Almost surely, 2^991931776 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 991931776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1181466000).

991931776 is an abundant number, since it is smaller than the sum of its proper divisors (1371000224).

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

991931776 is a wasteful number, since it uses less digits than its factorization.

991931776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1500 (or 1488 counting only the distinct ones).

The product of its digits is 642978, while the sum is 52.

The square root of 991931776 is about 31494.9484203420. The cubic root of 991931776 is about 997.3033264888.

The spelling of 991931776 in words is "nine hundred ninety-one million, nine hundred thirty-one thousand, seven hundred seventy-six".