79408678880021 has 4 divisors (see below), whose sum is σ = 79408780088844. Its totient is φ = 79408577671200.

The previous prime is 79408678880009. The next prime is 79408678880029. The reversal of 79408678880021 is 12008887680497.

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

It can be written as a sum of positive squares in 2 ways, for example, as 22840379863921 + 56568299016100 = 4779161^2 + 7521190^2 .

It is a cyclic number.

It is not a de Polignac number, because 79408678880021 - 2²⁶ = 79408611771157 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 (79408678880029) 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, 49418240 + ... + 50999801.

It is an arithmetic number, because the mean of its divisors is an integer number (19852195022211).

Almost surely, 2^{79408678880021} is an apocalyptic number.

It is an amenable number.

79408678880021 is a deficient number, since it is larger than the sum of its proper divisors (101208823).

79408678880021 is a wasteful number, since it uses less digits than its factorization.

79408678880021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101208822.

The product of its (nonzero) digits is 86704128, while the sum is 68.

The spelling of 79408678880021 in words is "seventy-nine trillion, four hundred eight billion, six hundred seventy-eight million, eight hundred eighty thousand, twenty-one".