201811 has 4 divisors (see below), whose sum is σ = 208800. Its totient is φ = 194824.

The previous prime is 201809. The next prime is 201821. The reversal of 201811 is 118102.

201811 = 69² + 70² + ... + 97².

201811 is nontrivially palindromic in base 4.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 118102 = 2 ⋅59051.

It is a cyclic number.

It is not a de Polignac number, because 201811 - 2¹ = 201809 is a prime.

201811 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 201791 and 201800.

It is not an unprimeable number, because it can be changed into a prime (201821) 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, 3451 + ... + 3508.

It is an arithmetic number, because the mean of its divisors is an integer number (52200).

2²⁰¹⁸¹¹ is an apocalyptic number.

201811 is a deficient number, since it is larger than the sum of its proper divisors (6989).

201811 is an equidigital number, since it uses as much as digits as its factorization.

201811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6988.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 201811 is about 449.2337921395. The cubic root of 201811 is about 58.6563378568.

Adding to 201811 its reverse (118102), we get a palindrome (319913).

The spelling of 201811 in words is "two hundred one thousand, eight hundred eleven".