9923685991 has 4 divisors (see below), whose sum is σ = 9966277152. Its totient is φ = 9881094832.

The previous prime is 9923685929. The next prime is 9923686013. The reversal of 9923685991 is 1995863299.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1995863299 = 29669 ⋅67271.

It is a cyclic number.

It is not a de Polignac number, because 9923685991 - 2²⁹ = 9386815079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9923685901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21295231 + ... + 21295696.

It is an arithmetic number, because the mean of its divisors is an integer number (2491569288).

Almost surely, 2^9923685991 is an apocalyptic number.

9923685991 is a deficient number, since it is larger than the sum of its proper divisors (42591161).

9923685991 is a wasteful number, since it uses less digits than its factorization.

9923685991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42591160.

The product of its digits is 9447840, while the sum is 61.

The square root of 9923685991 is about 99617.6991854359. The cubic root of 9923685991 is about 2148.9402378383.

The spelling of 9923685991 in words is "nine billion, nine hundred twenty-three million, six hundred eighty-five thousand, nine hundred ninety-one".