664999 has 8 divisors (see below), whose sum is σ = 718560. Its totient is φ = 613536.

The previous prime is 664997. The next prime is 665011. The reversal of 664999 is 999466.

664999 = 97² + 98² + ... + 142².

It is a happy number.

664999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 664999 - 2¹ = 664997 is a prime.

It is a Duffinian number.

664999 is a modest number, since divided by 999 gives 664 as remainder.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 169 + ... + 1165.

It is an arithmetic number, because the mean of its divisors is an integer number (89820).

2⁶⁶⁴⁹⁹⁹ is an apocalyptic number.

664999 is a deficient number, since it is larger than the sum of its proper divisors (53561).

664999 is a wasteful number, since it uses less digits than its factorization.

664999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1049.

The product of its digits is 104976, while the sum is 43.

The square root of 664999 is about 815.4747083754. The cubic root of 664999 is about 87.2851435999.

The spelling of 664999 in words is "six hundred sixty-four thousand, nine hundred ninety-nine".