664405 has 16 divisors (see below), whose sum is σ = 935424. Its totient is φ = 443520.

The previous prime is 664403. The next prime is 664421. The reversal of 664405 is 504466.

It is a happy number.

It is not a de Polignac number, because 664405 - 2¹ = 664403 is a prime.

It is an Ulam number.

It is a plaindrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 664405.

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 in 15 ways as a sum of consecutive naturals, for example, 1204 + ... + 1666.

It is an arithmetic number, because the mean of its divisors is an integer number (58464).

2⁶⁶⁴⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

664405 is a deficient number, since it is larger than the sum of its proper divisors (271019).

664405 is a wasteful number, since it uses less digits than its factorization.

664405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 664405 is about 815.1104219675. The cubic root of 664405 is about 87.2591471596.

The spelling of 664405 in words is "six hundred sixty-four thousand, four hundred five".