205511 has 4 divisors (see below), whose sum is σ = 207024. Its totient is φ = 204000.

The previous prime is 205507. The next prime is 205519. The reversal of 205511 is 115502.

205511 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, and also an emirpimes, since its reverse is a distinct semiprime: 115502 = 2 ⋅57751.

It is a cyclic number.

It is not a de Polignac number, because 205511 - 2² = 205507 is a prime.

It is a super-2 number, since 2×205511² = 84469542242, 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 (205519) 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, 530 + ... + 831.

It is an arithmetic number, because the mean of its divisors is an integer number (51756).

2²⁰⁵⁵¹¹ is an apocalyptic number.

205511 is a deficient number, since it is larger than the sum of its proper divisors (1513).

205511 is a wasteful number, since it uses less digits than its factorization.

205511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1512.

The product of its (nonzero) digits is 50, while the sum is 14.

The square root of 205511 is about 453.3332107843. Note that the first 3 decimals coincide. The cubic root of 205511 is about 59.0126373390.

Subtracting from 205511 its reverse (115502), we obtain a palindrome (90009).

The spelling of 205511 in words is "two hundred five thousand, five hundred eleven".