991523280 has 320 divisors, whose sum is σ = 3507204096. Its totient is φ = 229632000.

The previous prime is 991523263. The next prime is 991523293. The reversal of 991523280 is 82325199.

991523280 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7568815 + ... + 7568945.

Almost surely, 2^991523280 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 991523280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1753602048).

991523280 is an abundant number, since it is smaller than the sum of its proper divisors (2515680816).

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

991523280 is a wasteful number, since it uses less digits than its factorization.

991523280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266 (or 260 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 991523280 is about 31488.4626490402. The cubic root of 991523280 is about 997.1664049899.

The spelling of 991523280 in words is "nine hundred ninety-one million, five hundred twenty-three thousand, two hundred eighty".