664784 has 10 divisors (see below), whose sum is σ = 1288050. Its totient is φ = 332384.

The previous prime is 664777. The next prime is 664789. The reversal of 664784 is 487466.

It can be written as a sum of positive squares in only one way, i.e., 394384 + 270400 = 628^2 + 520^2 .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 664784.

It is not an unprimeable number, because it can be changed into a prime (664789) by changing a digit.

664784 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 20759 + ... + 20790.

It is an arithmetic number, because the mean of its divisors is an integer number (128805).

2⁶⁶⁴⁷⁸⁴ is an apocalyptic number.

It is an amenable number.

664784 is a deficient number, since it is larger than the sum of its proper divisors (623266).

664784 is a wasteful number, since it uses less digits than its factorization.

664784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41557 (or 41551 counting only the distinct ones).

The product of its digits is 32256, while the sum is 35.

The square root of 664784 is about 815.3428726616. The cubic root of 664784 is about 87.2757359022.

The spelling of 664784 in words is "six hundred sixty-four thousand, seven hundred eighty-four".