665684 has 18 divisors (see below), whose sum is σ = 1232154. Its totient is φ = 314640.

The previous prime is 665677. The next prime is 665713. The reversal of 665684 is 486566.

It can be written as a sum of positive squares in only one way, i.e., 521284 + 144400 = 722^2 + 380^2 .

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

665684 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 5 ways as a sum of consecutive naturals, for example, 1214 + ... + 1674.

It is an arithmetic number, because the mean of its divisors is an integer number (68453).

2⁶⁶⁵⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

665684 is a deficient number, since it is larger than the sum of its proper divisors (566470).

665684 is a wasteful number, since it uses less digits than its factorization.

665684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503 (or 482 counting only the distinct ones).

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

The square root of 665684 is about 815.8946010362. The cubic root of 665684 is about 87.3151034472.

The spelling of 665684 in words is "six hundred sixty-five thousand, six hundred eighty-four".