405684 has 36 divisors (see below), whose sum is σ = 1048320. Its totient is φ = 132240.

The previous prime is 405683. The next prime is 405689. The reversal of 405684 is 486504.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (405683) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2029 + ... + 2219.

It is an arithmetic number, because the mean of its divisors is an integer number (29120).

2⁴⁰⁵⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 405684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (524160).

405684 is an abundant number, since it is smaller than the sum of its proper divisors (642636).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

405684 is a wasteful number, since it uses less digits than its factorization.

405684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260 (or 255 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 405684 is about 636.9332775103. The cubic root of 405684 is about 74.0279903853.

It can be divided in two parts, 405 and 684, that added together give a square (1089 = 33²).

The spelling of 405684 in words is "four hundred five thousand, six hundred eighty-four".