405645 has 8 divisors (see below), whose sum is σ = 649056. Its totient is φ = 216336.

The previous prime is 405641. The next prime is 405659. The reversal of 405645 is 546504.

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

It is not a de Polignac number, because 405645 - 2² = 405641 is a prime.

It is a super-3 number, since 3×405645³ = 200244057341133375, which contains 333 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (405641) 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, 13507 + ... + 13536.

It is an arithmetic number, because the mean of its divisors is an integer number (81132).

2⁴⁰⁵⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

405645 is a deficient number, since it is larger than the sum of its proper divisors (243411).

405645 is a wasteful number, since it uses less digits than its factorization.

405645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27051.

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 405645 is about 636.9026613227. The cubic root of 405645 is about 74.0256181086.

The spelling of 405645 in words is "four hundred five thousand, six hundred forty-five".