664664 has 64 divisors (see below), whose sum is σ = 1693440. Its totient is φ = 236160.

The previous prime is 664663. The next prime is 664667. The reversal of 664664 is 466466.

664664 = T₅₇ + T₅₈ + ... + T₁₆₀.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 664664.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7967 + ... + 8049.

It is an arithmetic number, because the mean of its divisors is an integer number (26460).

2⁶⁶⁴⁶⁶⁴ 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 664664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (846720).

664664 is an abundant number, since it is smaller than the sum of its proper divisors (1028776).

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

664664 is a wasteful number, since it uses less digits than its factorization.

664664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120 (or 116 counting only the distinct ones).

The product of its digits is 20736, while the sum is 32.

The square root of 664664 is about 815.2692806674. The cubic root of 664664 is about 87.2704842121.

The spelling of 664664 in words is "six hundred sixty-four thousand, six hundred sixty-four".