211806 has 36 divisors (see below), whose sum is σ = 537576. Its totient is φ = 59040.

The previous prime is 211801. The next prime is 211811. The reversal of 211806 is 608112.

211806 is nontrivially palindromic in base 8.

211806 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (211801) and next prime (211811).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an Ulam number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 211806.

It is not an unprimeable number, because it can be changed into a prime (211801) by changing a digit.

211806 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 5146 + ... + 5186.

2²¹¹⁸⁰⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 211806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (268788).

211806 is an abundant number, since it is smaller than the sum of its proper divisors (325770).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

211806 is a wasteful number, since it uses less digits than its factorization.

211806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 211806 is about 460.2238585732. The cubic root of 211806 is about 59.6091258191.

Adding to 211806 its reverse (608112), we get a palindrome (819918).

The spelling of 211806 in words is "two hundred eleven thousand, eight hundred six".