20211 has 4 divisors (see below), whose sum is σ = 26952. Its totient is φ = 13472.

The previous prime is 20201. The next prime is 20219. The reversal of 20211 is 11202.

It is a happy number.

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 20211 - 2⁶ = 20147 is a prime.

It is a D-number.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 20211.

It is not an unprimeable number, because it can be changed into a prime (20219) 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, 3366 + ... + 3371.

It is an arithmetic number, because the mean of its divisors is an integer number (6738).

2²⁰²¹¹ is an apocalyptic number.

20211 is a deficient number, since it is larger than the sum of its proper divisors (6741).

20211 is an equidigital number, since it uses as much as digits as its factorization.

20211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6740.

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 20211 is about 142.1653966336. The cubic root of 20211 is about 27.2392994487.

Adding to 20211 its reverse (11202), we get a palindrome (31413).

Subtracting from 20211 its reverse (11202), we obtain a palindrome (9009).

It can be divided in two parts, 202 and 11, that multiplied together give a palindrome (2222).

The spelling of 20211 in words is "twenty thousand, two hundred eleven", and thus it is an iban number.