991012133331 has 24 divisors (see below), whose sum is σ = 1569442118400. Its totient is φ = 597595244400.

The previous prime is 991012133317. The next prime is 991012133339. The reversal of 991012133331 is 133331210199.

991012133331 is a `hidden beast` number, since 9 + 9 + 101 + 213 + 3 + 331 = 666.

It is not a de Polignac number, because 991012133331 - 2⁵ = 991012133299 is a prime.

It is a super-2 number, since 2×991012133331² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (991012133339) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25131615 + ... + 25171016.

It is an arithmetic number, because the mean of its divisors is an integer number (65393421600).

Almost surely, 2^991012133331 is an apocalyptic number.

991012133331 is a deficient number, since it is larger than the sum of its proper divisors (578429985069).

991012133331 is a wasteful number, since it uses less digits than its factorization.

991012133331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50302847 (or 50302844 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The spelling of 991012133331 in words is "nine hundred ninety-one billion, twelve million, one hundred thirty-three thousand, three hundred thirty-one".