405551 has 4 divisors (see below), whose sum is σ = 411672. Its totient is φ = 399432.

The previous prime is 405541. The next prime is 405553. The reversal of 405551 is 155504.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 405551 - 2⁶ = 405487 is a prime.

It is a super-2 number, since 2×405551² = 328943227202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (405553) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2960 + ... + 3093.

It is an arithmetic number, because the mean of its divisors is an integer number (102918).

2⁴⁰⁵⁵⁵¹ is an apocalyptic number.

405551 is a deficient number, since it is larger than the sum of its proper divisors (6121).

405551 is an equidigital number, since it uses as much as digits as its factorization.

405551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6120.

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 405551 is about 636.8288624112. The cubic root of 405551 is about 74.0198996884.

Subtracting from 405551 its reverse (155504), we obtain a cube (250047 = 63³).

The spelling of 405551 in words is "four hundred five thousand, five hundred fifty-one".