79721598991 has 4 divisors (see below), whose sum is σ = 84411104832. Its totient is φ = 75032093152.

The previous prime is 79721598961. The next prime is 79721598997. The reversal of 79721598991 is 19989512797.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 79721598991 - 2¹³ = 79721590799 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 (79721598997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2344752895 + ... + 2344752928.

It is an arithmetic number, because the mean of its divisors is an integer number (21102776208).

Almost surely, 2^79721598991 is an apocalyptic number.

79721598991 is a deficient number, since it is larger than the sum of its proper divisors (4689505841).

79721598991 is a wasteful number, since it uses less digits than its factorization.

79721598991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4689505840.

The product of its digits is 25719120, while the sum is 67.

The spelling of 79721598991 in words is "seventy-nine billion, seven hundred twenty-one million, five hundred ninety-eight thousand, nine hundred ninety-one".