79776307809 has 81 divisors (see below), whose sum is σ = 131941544371. Its totient is φ = 48196756080.

The previous prime is 79776307781. The next prime is 79776307823. The reversal of 79776307809 is 90870367797.

The square root of 79776307809 is 282447.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 4465580625 + 75310727184 = 66825^2 + 274428^2 .

It is a tau number, because it is divible by the number of its divisors (81).

It is not a de Polignac number, because 79776307809 - 2⁹ = 79776307297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (79776307309) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 251660119 + ... + 251660435.

Almost surely, 2^79776307809 is an apocalyptic number.

79776307809 is the 282447-th square number.

79776307809 is the 141224-th centered octagonal number.

It is an amenable number.

79776307809 is a deficient number, since it is larger than the sum of its proper divisors (52165236562).

79776307809 is an frugal number, since it uses more digits than its factorization.

79776307809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680 (or 331 counting only the distinct ones).

The product of its (nonzero) digits is 28005264, while the sum is 63.

The spelling of 79776307809 in words is "seventy-nine billion, seven hundred seventy-six million, three hundred seven thousand, eight hundred nine".