664406 has 4 divisors (see below), whose sum is σ = 996612. Its totient is φ = 332202.

The previous prime is 664403. The next prime is 664421. The reversal of 664406 is 604466.

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

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166100 + ... + 166103.

It is an arithmetic number, because the mean of its divisors is an integer number (249153).

2⁶⁶⁴⁴⁰⁶ is an apocalyptic number.

664406 is a deficient number, since it is larger than the sum of its proper divisors (332206).

664406 is a wasteful number, since it uses less digits than its factorization.

664406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332205.

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

The square root of 664406 is about 815.1110353811. Note that the first 3 decimals coincide. The cubic root of 664406 is about 87.2591909377.

The spelling of 664406 in words is "six hundred sixty-four thousand, four hundred six".