8391491764991 has 8 divisors (see below), whose sum is σ = 8395401045360. Its totient is φ = 8387583291648.

The previous prime is 8391491764969. The next prime is 8391491765003. The reversal of 8391491764991 is 1994671941938.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 8391491764991 - 2²⁶ = 8391424656127 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 (8391491764091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21121025 + ... + 21514661.

It is an arithmetic number, because the mean of its divisors is an integer number (1049425130670).

Almost surely, 2^{8391491764991} is an apocalyptic number.

8391491764991 is a deficient number, since it is larger than the sum of its proper divisors (3909280369).

8391491764991 is a wasteful number, since it uses less digits than its factorization.

8391491764991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403513.

The product of its digits is 105815808, while the sum is 71.

The spelling of 8391491764991 in words is "eight trillion, three hundred ninety-one billion, four hundred ninety-one million, seven hundred sixty-four thousand, nine hundred ninety-one".