664544 has 24 divisors (see below), whose sum is σ = 1378440. Its totient is φ = 314496.

The previous prime is 664537. The next prime is 664549. The reversal of 664544 is 445466.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62 + ... + 1154.

It is an arithmetic number, because the mean of its divisors is an integer number (57435).

2⁶⁶⁴⁵⁴⁴ 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 664544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (689220).

664544 is an abundant number, since it is smaller than the sum of its proper divisors (713896).

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

664544 is a wasteful number, since it uses less digits than its factorization.

664544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1122 (or 1114 counting only the distinct ones).

The product of its digits is 11520, while the sum is 29.

The square root of 664544 is about 815.1956820298. The cubic root of 664544 is about 87.2652318900.

The spelling of 664544 in words is "six hundred sixty-four thousand, five hundred forty-four".