405506 has 4 divisors (see below), whose sum is σ = 608262. Its totient is φ = 202752.

The previous prime is 405499. The next prime is 405521. The reversal of 405506 is 605504.

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

It can be written as a sum of positive squares in only one way, i.e., 312481 + 93025 = 559^2 + 305^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 101375 + ... + 101378.

2⁴⁰⁵⁵⁰⁶ is an apocalyptic number.

405506 is a deficient number, since it is larger than the sum of its proper divisors (202756).

405506 is a wasteful number, since it uses less digits than its factorization.

405506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202755.

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 405506 is about 636.7935301179. The cubic root of 405506 is about 74.0171618340.

The spelling of 405506 in words is "four hundred five thousand, five hundred six".