205643 has 4 divisors (see below), whose sum is σ = 214608. Its totient is φ = 196680.

The previous prime is 205633. The next prime is 205651. The reversal of 205643 is 346502.

205643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 205643 - 2⁴ = 205627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205603) 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, 4448 + ... + 4493.

It is an arithmetic number, because the mean of its divisors is an integer number (53652).

2²⁰⁵⁶⁴³ is an apocalyptic number.

205643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

205643 is a deficient number, since it is larger than the sum of its proper divisors (8965).

205643 is an equidigital number, since it uses as much as digits as its factorization.

205643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8964.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 205643 is about 453.4787756886. The cubic root of 205643 is about 59.0252692677.

It can be divided in two parts, 205 and 643, that added together give a palindrome (848).

The spelling of 205643 in words is "two hundred five thousand, six hundred forty-three".