665664 has 28 divisors (see below), whose sum is σ = 1761744. Its totient is φ = 221824.

The previous prime is 665659. The next prime is 665677. The reversal of 665664 is 466566.

It is an unprimeable number.

665664 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1542 + ... + 1925.

2⁶⁶⁵⁶⁶⁴ is an apocalyptic number.

665664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

665664 is an abundant number, since it is smaller than the sum of its proper divisors (1096080).

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

665664 is a wasteful number, since it uses less digits than its factorization.

665664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3482 (or 3472 counting only the distinct ones).

The product of its digits is 25920, while the sum is 33.

The square root of 665664 is about 815.8823444591. The cubic root of 665664 is about 87.3142289985.

Multiplying 665664 by its sum of digits (33), we get a palindrome (21966912).

The spelling of 665664 in words is "six hundred sixty-five thousand, six hundred sixty-four".