78866665 has 8 divisors (see below), whose sum is σ = 94689288. Its totient is φ = 63060480.

The previous prime is 78866639. The next prime is 78866677. The reversal of 78866665 is 56666887.

It can be written as a sum of positive squares in 4 ways, for example, as 30591961 + 48274704 = 5531^2 + 6948^2 .

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

It is not a de Polignac number, because 78866665 - 2⁵ = 78866633 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12729 + ... + 17881.

It is an arithmetic number, because the mean of its divisors is an integer number (11836161).

Almost surely, 2^78866665 is an apocalyptic number.

It is an amenable number.

78866665 is a deficient number, since it is larger than the sum of its proper divisors (15822623).

78866665 is a wasteful number, since it uses less digits than its factorization.

78866665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8219.

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

The square root of 78866665 is about 8880.6905699951. The cubic root of 78866665 is about 428.8425062546.

The spelling of 78866665 in words is "seventy-eight million, eight hundred sixty-six thousand, six hundred sixty-five".