78686665 has 8 divisors (see below), whose sum is σ = 94848768. Its totient is φ = 62666160.

The previous prime is 78686653. The next prime is 78686669. The reversal of 78686665 is 56668687.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78686665 - 2⁵ = 78686633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78686669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34171 + ... + 36400.

It is an arithmetic number, because the mean of its divisors is an integer number (11856096).

Almost surely, 2^78686665 is an apocalyptic number.

It is an amenable number.

78686665 is a deficient number, since it is larger than the sum of its proper divisors (16162103).

78686665 is a wasteful number, since it uses less digits than its factorization.

78686665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70799.

The product of its digits is 2903040, while the sum is 52.

The square root of 78686665 is about 8870.5504338795. The cubic root of 78686665 is about 428.5160039172.

The spelling of 78686665 in words is "seventy-eight million, six hundred eighty-six thousand, six hundred sixty-five".