664685 has 12 divisors (see below), whose sum is σ = 928188. Its totient is φ = 455616.

The previous prime is 664679. The next prime is 664687. The reversal of 664685 is 586466.

It can be written as a sum of positive squares in 2 ways, for example, as 499849 + 164836 = 707^2 + 406^2 .

It is not a de Polignac number, because 664685 - 2⁴ = 664669 is a prime.

It is a super-2 number, since 2×664685² = 883612298450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664687) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1112 + ... + 1601.

It is an arithmetic number, because the mean of its divisors is an integer number (77349).

2⁶⁶⁴⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

664685 is a deficient number, since it is larger than the sum of its proper divisors (263503).

664685 is a wasteful number, since it uses less digits than its factorization.

664685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2732 (or 2725 counting only the distinct ones).

The product of its digits is 34560, while the sum is 35.

The square root of 664685 is about 815.2821597459. The cubic root of 664685 is about 87.2714033035.

The spelling of 664685 in words is "six hundred sixty-four thousand, six hundred eighty-five".