664669 has 2 divisors, whose sum is σ = 664670. Its totient is φ = 664668.

The previous prime is 664667. The next prime is 664679. The reversal of 664669 is 966466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 532900 + 131769 = 730^2 + 363^2 .

It is a cyclic number.

It is not a de Polignac number, because 664669 - 2¹ = 664667 is a prime.

It is a super-2 number, since 2×664669² = 883569759122, which contains 22 as substring.

Together with 664667, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332334 + 332335.

It is an arithmetic number, because the mean of its divisors is an integer number (332335).

2⁶⁶⁴⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

664669 is a deficient number, since it is larger than the sum of its proper divisors (1).

664669 is an equidigital number, since it uses as much as digits as its factorization.

664669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46656, while the sum is 37.

The square root of 664669 is about 815.2723471332. The cubic root of 664669 is about 87.2707030452.

The spelling of 664669 in words is "six hundred sixty-four thousand, six hundred sixty-nine".