991123872 has 24 divisors (see below), whose sum is σ = 2601700416. Its totient is φ = 330374592.

The previous prime is 991123871. The next prime is 991123877. The reversal of 991123872 is 278321199.

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (991123871) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5162008 + ... + 5162199.

It is an arithmetic number, because the mean of its divisors is an integer number (108404184).

Almost surely, 2^991123872 is an apocalyptic number.

It is an amenable number.

991123872 is an abundant number, since it is smaller than the sum of its proper divisors (1610576544).

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

991123872 is a wasteful number, since it uses less digits than its factorization.

991123872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10324220 (or 10324212 counting only the distinct ones).

The product of its digits is 54432, while the sum is 42.

The square root of 991123872 is about 31482.1198777973. The cubic root of 991123872 is about 997.0324932813.

The spelling of 991123872 in words is "nine hundred ninety-one million, one hundred twenty-three thousand, eight hundred seventy-two".