666444 has 48 divisors (see below), whose sum is σ = 1702400. Its totient is φ = 202176.

The previous prime is 666439. The next prime is 666461. The reversal of 666444 is 444666.

666444 = T₁₇₁ + T₁₇₂ + ... + T₂₀₇.

It is a nude number because it is divisible by every one of its digits.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is an unprimeable number.

It is an upside-down number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8397 + ... + 8475.

2⁶⁶⁶⁴⁴⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (851200).

666444 is an abundant number, since it is smaller than the sum of its proper divisors (1035956).

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

666444 is a wasteful number, since it uses less digits than its factorization.

666444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142 (or 140 counting only the distinct ones).

The product of its digits is 13824, while the sum is 30.

The square root of 666444 is about 816.3602146112. The cubic root of 666444 is about 87.3483195281.

The spelling of 666444 in words is "six hundred sixty-six thousand, four hundred forty-four".