666666678 has 8 divisors (see below), whose sum is σ = 1333333368. Its totient is φ = 222222224.

The previous prime is 666666667. The next prime is 666666691. The reversal of 666666678 is 876666666.

It is a happy number.

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

666666678 is an admirable number.

It is a Curzon number.

It is a plaindrome in base 10.

It is a congruent number.

It is an unprimeable number.

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, 55555551 + ... + 55555562.

It is an arithmetic number, because the mean of its divisors is an integer number (166666671).

Almost surely, 2^666666678 is an apocalyptic number.

666666678 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666666678 is a wasteful number, since it uses less digits than its factorization.

666666678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111111118.

The product of its digits is 15676416, while the sum is 57.

The square root of 666666678 is about 25819.8891941852. The cubic root of 666666678 is about 873.5804696866.

The spelling of 666666678 in words is "six hundred sixty-six million, six hundred sixty-six thousand, six hundred seventy-eight".