79219921997 has 4 divisors (see below), whose sum is σ = 79221161376. Its totient is φ = 79218682620.

The previous prime is 79219921909. The next prime is 79219922009. The reversal of 79219921997 is 79912991297.

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, and also an emirpimes, since its reverse is a distinct semiprime: 79912991297 = 7127 ⋅11212711.

It is a cyclic number.

It is not a de Polignac number, because 79219921997 - 2²⁴ = 79203144781 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 (79219921397) 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, 518279 + ... + 653492.

It is an arithmetic number, because the mean of its divisors is an integer number (19805290344).

Almost surely, 2^79219921997 is an apocalyptic number.

It is an amenable number.

79219921997 is a deficient number, since it is larger than the sum of its proper divisors (1239379).

79219921997 is a wasteful number, since it uses less digits than its factorization.

79219921997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1239378.

The product of its digits is 11573604, while the sum is 65.

The spelling of 79219921997 in words is "seventy-nine billion, two hundred nineteen million, nine hundred twenty-one thousand, nine hundred ninety-seven".