211813 has 4 divisors (see below), whose sum is σ = 242080. Its totient is φ = 181548.

The previous prime is 211811. The next prime is 211817. The reversal of 211813 is 318112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 211813 - 2¹ = 211811 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15123 + ... + 15136.

It is an arithmetic number, because the mean of its divisors is an integer number (60520).

2²¹¹⁸¹³ is an apocalyptic number.

It is an amenable number.

211813 is a deficient number, since it is larger than the sum of its proper divisors (30267).

211813 is an equidigital number, since it uses as much as digits as its factorization.

211813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30266.

The product of its digits is 48, while the sum is 16.

The square root of 211813 is about 460.2314635050. The cubic root of 211813 is about 59.6097824881.

Adding to 211813 its reverse (318112), we get a palindrome (529925).

It can be divided in two parts, 211 and 813, that added together give a 10-th power (1024 = 2¹⁰).

The spelling of 211813 in words is "two hundred eleven thousand, eight hundred thirteen".