991091000 has 32 divisors (see below), whose sum is σ = 2319155280. Its totient is φ = 396436000.

The previous prime is 991090967. The next prime is 991091009. The reversal of 991091000 is 190199.

991091000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×991091000² = 1964522740562000000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991091009) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 494546 + ... + 496545.

Almost surely, 2^991091000 is an apocalyptic number.

It is an amenable number.

991091000 is an abundant number, since it is smaller than the sum of its proper divisors (1328064280).

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

991091000 is a wasteful number, since it uses less digits than its factorization.

991091000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 991112 (or 991098 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 991091000 is about 31481.5977993494. The cubic root of 991091000 is about 997.0214705035.

The spelling of 991091000 in words is "nine hundred ninety-one million, ninety-one thousand".