666684 has 24 divisors (see below), whose sum is σ = 1728720. Its totient is φ = 222192.

The previous prime is 666683. The next prime is 666697. The reversal of 666684 is 486666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666683) 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, 2979 + ... + 3194.

It is an arithmetic number, because the mean of its divisors is an integer number (72030).

2⁶⁶⁶⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

666684 is an abundant number, since it is smaller than the sum of its proper divisors (1062036).

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

666684 is a wasteful number, since it uses less digits than its factorization.

666684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6186 (or 6178 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 666684 is about 816.5071953143. The cubic root of 666684 is about 87.3588035701.

It can be divided in two parts, 66 and 6684, that multiplied together give a palindrome (441144).

The spelling of 666684 in words is "six hundred sixty-six thousand, six hundred eighty-four".