2161811 has 4 divisors (see below), whose sum is σ = 2164800. Its totient is φ = 2158824.

The previous prime is 2161787. The next prime is 2161813. The reversal of 2161811 is 1181612.

2161811 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 2161811 - 2¹⁰ = 2160787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161813) 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, 350 + ... + 2108.

It is an arithmetic number, because the mean of its divisors is an integer number (541200).

2^2161811 is an apocalyptic number.

2161811 is a deficient number, since it is larger than the sum of its proper divisors (2989).

2161811 is a wasteful number, since it uses less digits than its factorization.

2161811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2988.

The product of its digits is 96, while the sum is 20.

The square root of 2161811 is about 1470.3098312941. The cubic root of 2161811 is about 129.3021979881.

It can be divided in two parts, 2161 and 811, that multiplied together give a palindrome (1752571).

The spelling of 2161811 in words is "two million, one hundred sixty-one thousand, eight hundred eleven".