206405 has 4 divisors (see below), whose sum is σ = 247692. Its totient is φ = 165120.

The previous prime is 206399. The next prime is 206407. The reversal of 206405 is 504602.

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

It can be written as a sum of positive squares in 2 ways, for example, as 81796 + 124609 = 286^2 + 353^2 .

It is not a de Polignac number, because 206405 - 2⁶ = 206341 is a prime.

It is a Duffinian number.

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 206405.

It is not an unprimeable number, because it can be changed into a prime (206407) 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, 20636 + ... + 20645.

It is an arithmetic number, because the mean of its divisors is an integer number (61923).

2²⁰⁶⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

206405 is a deficient number, since it is larger than the sum of its proper divisors (41287).

206405 is an equidigital number, since it uses as much as digits as its factorization.

206405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41286.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 206405 is about 454.3181704489. The cubic root of 206405 is about 59.0980844792.

The spelling of 206405 in words is "two hundred six thousand, four hundred five".