991071880 has 32 divisors (see below), whose sum is σ = 2266473240. Its totient is φ = 389928960.

The previous prime is 991071859. The next prime is 991071881. The reversal of 991071880 is 88170199.

It can be written as a sum of positive squares in 4 ways, for example, as 813276324 + 177795556 = 28518^2 + 13334^2 .

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (991071881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 200649 + ... + 205528.

Almost surely, 2^991071880 is an apocalyptic number.

It is an amenable number.

991071880 is an abundant number, since it is smaller than the sum of its proper divisors (1275401360).

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

991071880 is a wasteful number, since it uses less digits than its factorization.

991071880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406249 (or 406245 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 991071880 is about 31481.2941284185. The cubic root of 991071880 is about 997.0150589923.

The spelling of 991071880 in words is "nine hundred ninety-one million, seventy-one thousand, eight hundred eighty".