78656665687 has 4 divisors (see below), whose sum is σ = 78657640360. Its totient is φ = 78655691016.

The previous prime is 78656665651. The next prime is 78656665691.

78656665687 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is not a de Polignac number, because 78656665687 - 2²³ = 78648277079 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 (78656665387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 354153 + ... + 531730.

It is an arithmetic number, because the mean of its divisors is an integer number (19664410090).

Almost surely, 2^78656665687 is an apocalyptic number.

78656665687 is a deficient number, since it is larger than the sum of its proper divisors (974673).

78656665687 is an equidigital number, since it uses as much as digits as its factorization.

78656665687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 974672.

The product of its digits is 609638400, while the sum is 70.

The spelling of 78656665687 in words is "seventy-eight billion, six hundred fifty-six million, six hundred sixty-five thousand, six hundred eighty-seven".