8757991921 has 6 divisors (see below), whose sum is σ = 10187868210. Its totient is φ = 7506850176.

The previous prime is 8757991873. The next prime is 8757991987. The reversal of 8757991921 is 1291997578.

It can be written as a sum of positive squares in only one way, i.e., 7562215521 + 1195776400 = 86961^2 + 34580^2 .

It is not a de Polignac number, because 8757991921 - 2¹⁵ = 8757959153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8757991621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 89367216 + ... + 89367313.

It is an arithmetic number, because the mean of its divisors is an integer number (1697978035).

Almost surely, 2^8757991921 is an apocalyptic number.

It is an amenable number.

8757991921 is a deficient number, since it is larger than the sum of its proper divisors (1429876289).

8757991921 is a wasteful number, since it uses less digits than its factorization.

8757991921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178734543 (or 178734536 counting only the distinct ones).

The product of its digits is 2857680, while the sum is 58.

The square root of 8757991921 is about 93584.1435340411. The cubic root of 8757991921 is about 2061.2698301675.

The spelling of 8757991921 in words is "eight billion, seven hundred fifty-seven million, nine hundred ninety-one thousand, nine hundred twenty-one".