665606644 has 12 divisors (see below), whose sum is σ = 1233330084. Its totient is φ = 313226624.

The previous prime is 665606629. The next prime is 665606657. The reversal of 665606644 is 446606566.

It can be written as a sum of positive squares in 2 ways, for example, as 467078544 + 198528100 = 21612^2 + 14090^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 665606644.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 4894099 + ... + 4894234.

It is an arithmetic number, because the mean of its divisors is an integer number (102777507).

Almost surely, 2^665606644 is an apocalyptic number.

It is an amenable number.

665606644 is a deficient number, since it is larger than the sum of its proper divisors (567723440).

665606644 is a wasteful number, since it uses less digits than its factorization.

665606644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9788354 (or 9788352 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 43.

The square root of 665606644 is about 25799.3535577929. The cubic root of 665606644 is about 873.1172115732.

The spelling of 665606644 in words is "six hundred sixty-five million, six hundred six thousand, six hundred forty-four".