666405 has 24 divisors (see below), whose sum is σ = 1179360. Its totient is φ = 348000.

The previous prime is 666403. The next prime is 666427. The reversal of 666405 is 504666.

It is not a de Polignac number, because 666405 - 2¹ = 666403 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2530 + ... + 2780.

It is an arithmetic number, because the mean of its divisors is an integer number (49140).

2⁶⁶⁶⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

666405 is a deficient number, since it is larger than the sum of its proper divisors (512955).

666405 is a wasteful number, since it uses less digits than its factorization.

666405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321 (or 318 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 666405 is about 816.3363277473. The cubic root of 666405 is about 87.3466156336.

The spelling of 666405 in words is "six hundred sixty-six thousand, four hundred five".