665939644 has 24 divisors (see below), whose sum is σ = 1244476800. Its totient is φ = 311115840.

The previous prime is 665939639. The next prime is 665939689. The reversal of 665939644 is 446939566.

It is a junction number, because it is equal to n+sod(n) for n = 665939591 and 665939600.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88999 + ... + 96190.

It is an arithmetic number, because the mean of its divisors is an integer number (51853200).

Almost surely, 2^665939644 is an apocalyptic number.

It is an amenable number.

665939644 is a deficient number, since it is larger than the sum of its proper divisors (578537156).

665939644 is a wasteful number, since it uses less digits than its factorization.

665939644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185253 (or 185251 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 52.

The square root of 665939644 is about 25805.8064008858. The cubic root of 665939644 is about 873.2627928315.

The spelling of 665939644 in words is "six hundred sixty-five million, nine hundred thirty-nine thousand, six hundred forty-four".