78666687 has 16 divisors (see below), whose sum is σ = 127138560. Its totient is φ = 47676600.

The previous prime is 78666677. The next prime is 78666697.

78666687 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (78666677) and next prime (78666697).

It is not a de Polignac number, because 78666687 - 2⁴ = 78666671 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78666677) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 132139 + ... + 132732.

It is an arithmetic number, because the mean of its divisors is an integer number (7946160).

Almost surely, 2^78666687 is an apocalyptic number.

78666687 is a deficient number, since it is larger than the sum of its proper divisors (48471873).

78666687 is a wasteful number, since it uses less digits than its factorization.

78666687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264891 (or 264885 counting only the distinct ones).

The product of its digits is 4064256, while the sum is 54.

The square root of 78666687 is about 8869.4242766935. The cubic root of 78666687 is about 428.4797350977.

The spelling of 78666687 in words is "seventy-eight million, six hundred sixty-six thousand, six hundred eighty-seven".