991255320 has 384 divisors, whose sum is σ = 3723632640. Its totient is φ = 235146240.

The previous prime is 991255313. The next prime is 991255337. The reversal of 991255320 is 23552199.

It is a happy number.

991255320 is a `hidden beast` number, since 99 + 12 + 553 + 2 + 0 = 666.

991255320 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7805097 + ... + 7805223.

It is an arithmetic number, because the mean of its divisors is an integer number (9696960).

Almost surely, 2^991255320 is an apocalyptic number.

991255320 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 991255320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1861816320).

991255320 is an abundant number, since it is smaller than the sum of its proper divisors (2732377320).

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

991255320 is a wasteful number, since it uses less digits than its factorization.

991255320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237 (or 221 counting only the distinct ones).

The product of its (nonzero) digits is 24300, while the sum is 36.

The square root of 991255320 is about 31484.2074697776. The cubic root of 991255320 is about 997.0765685435.

The spelling of 991255320 in words is "nine hundred ninety-one million, two hundred fifty-five thousand, three hundred twenty".