668644 has 12 divisors (see below), whose sum is σ = 1239084. Its totient is φ = 314624.

The previous prime is 668623. The next prime is 668671. The reversal of 668644 is 446866.

668644 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 438244 + 230400 = 662^2 + 480^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4849 + ... + 4984.

It is an arithmetic number, because the mean of its divisors is an integer number (103257).

2⁶⁶⁸⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

668644 is a deficient number, since it is larger than the sum of its proper divisors (570440).

668644 is a wasteful number, since it uses less digits than its factorization.

668644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9854 (or 9852 counting only the distinct ones).

The product of its digits is 27648, while the sum is 34.

The square root of 668644 is about 817.7065488303. The cubic root of 668644 is about 87.4443292135. Note that the first 3 decimals are identical.

The spelling of 668644 in words is "six hundred sixty-eight thousand, six hundred forty-four".