660644 has 6 divisors (see below), whose sum is σ = 1156134. Its totient is φ = 330320.

The previous prime is 660643. The next prime is 660659. The reversal of 660644 is 446066.

It can be written as a sum of positive squares in only one way, i.e., 422500 + 238144 = 650^2 + 488^2 .

It is not an unprimeable number, because it can be changed into a prime (660643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82577 + ... + 82584.

It is an arithmetic number, because the mean of its divisors is an integer number (192689).

2⁶⁶⁰⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

660644 is a deficient number, since it is larger than the sum of its proper divisors (495490).

660644 is a wasteful number, since it uses less digits than its factorization.

660644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165165 (or 165163 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 660644 is about 812.8000984252. The cubic root of 660644 is about 87.0941861024.

The spelling of 660644 in words is "six hundred sixty thousand, six hundred forty-four".