666678 has 16 divisors (see below), whose sum is σ = 1391616. Its totient is φ = 212520.

The previous prime is 666671. The next prime is 666683. The reversal of 666678 is 876666.

666678 is nontrivially palindromic in base 7.

It is a Curzon number.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666671) 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, 2278 + ... + 2553.

It is an arithmetic number, because the mean of its divisors is an integer number (86976).

2⁶⁶⁶⁶⁷⁸ is an apocalyptic number.

666678 is an abundant number, since it is smaller than the sum of its proper divisors (724938).

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

666678 is a wasteful number, since it uses less digits than its factorization.

666678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4859.

The product of its digits is 72576, while the sum is 39.

The square root of 666678 is about 816.5035211192. The cubic root of 666678 is about 87.3585414998.

The spelling of 666678 in words is "six hundred sixty-six thousand, six hundred seventy-eight".