20205 has 12 divisors (see below), whose sum is σ = 35100. Its totient is φ = 10752.

The previous prime is 20201. The next prime is 20219. The reversal of 20205 is 50202.

It can be written as a sum of positive squares in 2 ways, for example, as 9801 + 10404 = 99^2 + 102^2 .

It is not a de Polignac number, because 20205 - 2² = 20201 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 180 + ... + 269.

It is an arithmetic number, because the mean of its divisors is an integer number (2925).

2²⁰²⁰⁵ is an apocalyptic number.

It is an amenable number.

20205 is a deficient number, since it is larger than the sum of its proper divisors (14895).

20205 is a wasteful number, since it uses less digits than its factorization.

20205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 9.

The square root of 20205 is about 142.1442928858. The cubic root of 20205 is about 27.2366036895.

Adding to 20205 its reverse (50202), we get a palindrome (70407).

It can be divided in two parts, 2020 and 5, that added together give a square (2025 = 45²).

The spelling of 20205 in words is "twenty thousand, two hundred five".