405631 has 8 divisors (see below), whose sum is σ = 439280. Its totient is φ = 373248.

The previous prime is 405611. The next prime is 405641. The reversal of 405631 is 136504.

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

It is a 9-Lehmer number, since φ(405631) divides (405631-1)⁹.

It is a cyclic number.

It is not a de Polignac number, because 405631 - 2⁵ = 405599 is a prime.

It is a super-2 number, since 2×405631² = 329073016322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a zygodrome in base 2.

It is a junction number, because it is equal to n+sod(n) for n = 405599 and 405608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (405611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 415 + ... + 991.

It is an arithmetic number, because the mean of its divisors is an integer number (54910).

2⁴⁰⁵⁶³¹ is an apocalyptic number.

405631 is a deficient number, since it is larger than the sum of its proper divisors (33649).

405631 is a wasteful number, since it uses less digits than its factorization.

405631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 633.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 405631 is about 636.8916705375. The cubic root of 405631 is about 74.0247664849.

It can be divided in two parts, 40 and 5631, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 405631 in words is "four hundred five thousand, six hundred thirty-one".