8991372731 has 12 divisors (see below), whose sum is σ = 9957409560. Its totient is φ = 8051931360.

The previous prime is 8991372683. The next prime is 8991372749. The reversal of 8991372731 is 1372731998.

It is not a de Polignac number, because 8991372731 - 2²² = 8987178427 is a prime.

It is a super-2 number, since 2×8991372731² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 8991372731.

It is not an unprimeable number, because it can be changed into a prime (8991372431) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41666 + ... + 140423.

It is an arithmetic number, because the mean of its divisors is an integer number (829784130).

Almost surely, 2^8991372731 is an apocalyptic number.

8991372731 is a deficient number, since it is larger than the sum of its proper divisors (966036829).

8991372731 is a wasteful number, since it uses less digits than its factorization.

8991372731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182234 (or 182167 counting only the distinct ones).

The product of its digits is 571536, while the sum is 50.

The square root of 8991372731 is about 94822.8492031325. The cubic root of 8991372731 is about 2079.4189645401.

The spelling of 8991372731 in words is "eight billion, nine hundred ninety-one million, three hundred seventy-two thousand, seven hundred thirty-one".