79719836821 has 4 divisors (see below), whose sum is σ = 79720758144. Its totient is φ = 79718915500.

The previous prime is 79719836743. The next prime is 79719836869. The reversal of 79719836821 is 12863891797.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 79719836821 - 2²⁹ = 79182965909 is a prime.

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 79719836821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79719836621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 315655 + ... + 508996.

It is an arithmetic number, because the mean of its divisors is an integer number (19930189536).

Almost surely, 2^79719836821 is an apocalyptic number.

It is an amenable number.

79719836821 is a deficient number, since it is larger than the sum of its proper divisors (921323).

79719836821 is an equidigital number, since it uses as much as digits as its factorization.

79719836821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921322.

The product of its digits is 9144576, while the sum is 61.

The spelling of 79719836821 in words is "seventy-nine billion, seven hundred nineteen million, eight hundred thirty-six thousand, eight hundred twenty-one".