664538 has 12 divisors (see below), whose sum is σ = 1159722. Its totient is φ = 284760.

The previous prime is 664537. The next prime is 664549. The reversal of 664538 is 835466.

664538 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 only one way, i.e., 582169 + 82369 = 763^2 + 287^2 .

It is a super-2 number, since 2×664538² = 883221506888, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (664537) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3293 + ... + 3488.

2⁶⁶⁴⁵³⁸ is an apocalyptic number.

664538 is a deficient number, since it is larger than the sum of its proper divisors (495184).

664538 is a wasteful number, since it uses less digits than its factorization.

664538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6797 (or 6790 counting only the distinct ones).

The product of its digits is 17280, while the sum is 32.

The square root of 664538 is about 815.1920019235. The cubic root of 664538 is about 87.2649692572.

The spelling of 664538 in words is "six hundred sixty-four thousand, five hundred thirty-eight".