665643606 has 32 divisors (see below), whose sum is σ = 1402790400. Its totient is φ = 209988000.

The previous prime is 665643557. The next prime is 665643607. The reversal of 665643606 is 606346566.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665643607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 137731 + ... + 142481.

It is an arithmetic number, because the mean of its divisors is an integer number (43837200).

Almost surely, 2^665643606 is an apocalyptic number.

665643606 is an abundant number, since it is smaller than the sum of its proper divisors (737146794).

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

665643606 is a wasteful number, since it uses less digits than its factorization.

665643606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6004.

The product of its (nonzero) digits is 466560, while the sum is 42.

The square root of 665643606 is about 25800.0698836263. The cubic root of 665643606 is about 873.1333730510.

The spelling of 665643606 in words is "six hundred sixty-five million, six hundred forty-three thousand, six hundred six".