9991324785 has 72 divisors (see below), whose sum is σ = 17797086720. Its totient is φ = 4784203008.

The previous prime is 9991324771. The next prime is 9991324787. The reversal of 9991324785 is 5874231999.

It is not a de Polignac number, because 9991324785 - 2⁵ = 9991324753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9991324787) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 3468976 + ... + 3471854.

It is an arithmetic number, because the mean of its divisors is an integer number (247181760).

Almost surely, 2^9991324785 is an apocalyptic number.

It is an amenable number.

9991324785 is a deficient number, since it is larger than the sum of its proper divisors (7805761935).

9991324785 is a wasteful number, since it uses less digits than its factorization.

9991324785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2987 (or 2937 counting only the distinct ones).

The product of its digits is 4898880, while the sum is 57.

The square root of 9991324785 is about 99956.6145134978. The cubic root of 9991324785 is about 2153.8115036499.

The spelling of 9991324785 in words is "nine billion, nine hundred ninety-one million, three hundred twenty-four thousand, seven hundred eighty-five".