78646664687 has 4 divisors (see below), whose sum is σ = 78647412936. Its totient is φ = 78645916440.

The previous prime is 78646664671. The next prime is 78646664737.

78646664687 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 78646664687 - 2⁴ = 78646664671 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 (78646664617) 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, 184388 + ... + 437369.

It is an arithmetic number, because the mean of its divisors is an integer number (19661853234).

Almost surely, 2^78646664687 is an apocalyptic number.

78646664687 is a deficient number, since it is larger than the sum of its proper divisors (748249).

78646664687 is a wasteful number, since it uses less digits than its factorization.

78646664687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748248.

The product of its digits is 390168576, while the sum is 68.

The spelling of 78646664687 in words is "seventy-eight billion, six hundred forty-six million, six hundred sixty-four thousand, six hundred eighty-seven".