205311 has 4 divisors (see below), whose sum is σ = 273752.
Its totient is φ = 136872.
The previous prime is 205307. The next prime is 205319. The reversal of 205311 is 113502.
It is a semiprime because it is the product of two primes.
It is not a de Polignac number, because 205311 - 22 = 205307 is a prime.
It is a D-number.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (205319) 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, 34216 + ... + 34221.
It is an arithmetic number, because the mean of its divisors is an integer number (68438).
2205311 is an apocalyptic number.
205311 is a deficient number, since it is larger than the sum of its proper divisors (68441).
205311 is an equidigital number, since it uses as much as digits as its factorization.
205311 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 68440.
The product of its (nonzero) digits is 30, while the sum is 12.
The square root of 205311 is about 453.1125687950.
The cubic root of 205311 is about 58.9934877424.
Adding to 205311 its reverse (113502), we get a palindrome (318813).
Subtracting from 205311 its reverse (113502), we obtain a square (91809 = 3032).
The spelling of 205311 in words is "two hundred five thousand, three hundred eleven".