405621 has 16 divisors (see below), whose sum is σ = 611520. Its totient is φ = 265680.

The previous prime is 405611. The next prime is 405641. The reversal of 405621 is 126504.

It is a happy number.

405621 is a `hidden beast` number, since 40 + 5 + 621 = 666.

It is not a de Polignac number, because 405621 - 2¹⁰ = 404597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 405594 and 405603.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 405621.

It is not an unprimeable number, because it can be changed into a prime (405611) 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, 2151 + ... + 2331.

It is an arithmetic number, because the mean of its divisors is an integer number (38220).

2⁴⁰⁵⁶²¹ is an apocalyptic number.

It is an amenable number.

405621 is a deficient number, since it is larger than the sum of its proper divisors (205899).

405621 is a wasteful number, since it uses less digits than its factorization.

405621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273 (or 267 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 405621 is about 636.8838198604. The cubic root of 405621 is about 74.0241581704.

The spelling of 405621 in words is "four hundred five thousand, six hundred twenty-one".