665604 has 24 divisors (see below), whose sum is σ = 1725920. Its totient is φ = 221832.

The previous prime is 665603. The next prime is 665617. The reversal of 665604 is 406566.

665604 is a `hidden beast` number, since 6 + 656 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (665603) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 2974 + ... + 3189.

2⁶⁶⁵⁶⁰⁴ is an apocalyptic number.

It is an amenable number.

665604 is an abundant number, since it is smaller than the sum of its proper divisors (1060316).

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

665604 is a wasteful number, since it uses less digits than its factorization.

665604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6176 (or 6168 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 665604 is about 815.8455736229. The cubic root of 665604 is about 87.3116055472.

It can be divided in two parts, 66560 and 4, that added together give a square (66564 = 258²).

The spelling of 665604 in words is "six hundred sixty-five thousand, six hundred four".