79944809521 has 4 divisors (see below), whose sum is σ = 81039943972. Its totient is φ = 78849675072.

The previous prime is 79944809491. The next prime is 79944809537. The reversal of 79944809521 is 12590844997.

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 43172528400 + 36772281121 = 207780^2 + 191761^2 .

It is a cyclic number.

It is not a de Polignac number, because 79944809521 - 2¹⁷ = 79944678449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (79944809561) 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, 547567116 + ... + 547567261.

It is an arithmetic number, because the mean of its divisors is an integer number (20259985993).

Almost surely, 2^79944809521 is an apocalyptic number.

It is an amenable number.

79944809521 is a deficient number, since it is larger than the sum of its proper divisors (1095134451).

79944809521 is a wasteful number, since it uses less digits than its factorization.

79944809521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095134450.

The product of its (nonzero) digits is 6531840, while the sum is 58.

The spelling of 79944809521 in words is "seventy-nine billion, nine hundred forty-four million, eight hundred nine thousand, five hundred twenty-one".