79666681865 has 4 divisors (see below), whose sum is σ = 95600018244. Its totient is φ = 63733345488.

The previous prime is 79666681847. The next prime is 79666681879. The reversal of 79666681865 is 56818666697.

It is a happy number.

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 42943858441 + 36722823424 = 207229^2 + 191632^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79666681865 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 79666681795 and 79666681804.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7966668182 + ... + 7966668191.

It is an arithmetic number, because the mean of its divisors is an integer number (23900004561).

Almost surely, 2^79666681865 is an apocalyptic number.

It is an amenable number.

79666681865 is a deficient number, since it is larger than the sum of its proper divisors (15933336379).

79666681865 is a wasteful number, since it uses less digits than its factorization.

79666681865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15933336378.

The product of its digits is 156764160, while the sum is 68.

The spelling of 79666681865 in words is "seventy-nine billion, six hundred sixty-six million, six hundred eighty-one thousand, eight hundred sixty-five".