666818 has 8 divisors (see below), whose sum is σ = 1017360. Its totient is φ = 327700.

The previous prime is 666811. The next prime is 666821. The reversal of 666818 is 818666.

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

It is not an unprimeable number, because it can be changed into a prime (666811) by changing a digit.

666818 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2708 + ... + 2943.

It is an arithmetic number, because the mean of its divisors is an integer number (127170).

2⁶⁶⁶⁸¹⁸ is an apocalyptic number.

666818 is a deficient number, since it is larger than the sum of its proper divisors (350542).

666818 is a wasteful number, since it uses less digits than its factorization.

666818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5712.

The product of its digits is 13824, while the sum is 35.

The square root of 666818 is about 816.5892480311. The cubic root of 666818 is about 87.3646560657.

The spelling of 666818 in words is "six hundred sixty-six thousand, eight hundred eighteen".