664945 has 4 divisors (see below), whose sum is σ = 797940. Its totient is φ = 531952.

The previous prime is 664933. The next prime is 664949. The reversal of 664945 is 549466.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 112896 + 552049 = 336^2 + 743^2 .

It is a cyclic number.

It is not a de Polignac number, because 664945 - 2¹¹ = 662897 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 664945.

It is not an unprimeable number, because it can be changed into a prime (664949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66490 + ... + 66499.

It is an arithmetic number, because the mean of its divisors is an integer number (199485).

2⁶⁶⁴⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

664945 is a deficient number, since it is larger than the sum of its proper divisors (132995).

664945 is a wasteful number, since it uses less digits than its factorization.

664945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132994.

The product of its digits is 25920, while the sum is 34.

The square root of 664945 is about 815.4415981540. The cubic root of 664945 is about 87.2827809270.

The spelling of 664945 in words is "six hundred sixty-four thousand, nine hundred forty-five".