211223261 has 2 divisors, whose sum is σ = 211223262. Its totient is φ = 211223260.

The previous prime is 211223251. The next prime is 211223263. The reversal of 211223261 is 162322112.

211223261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 159239161 + 51984100 = 12619^2 + 7210^2 .

It is a cyclic number.

It is not a de Polignac number, because 211223261 - 2¹⁰ = 211222237 is a prime.

It is a Sophie Germain prime.

Together with 211223263, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211223263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105611630 + 105611631.

It is an arithmetic number, because the mean of its divisors is an integer number (105611631).

Almost surely, 2^211223261 is an apocalyptic number.

It is an amenable number.

211223261 is a deficient number, since it is larger than the sum of its proper divisors (1).

211223261 is an equidigital number, since it uses as much as digits as its factorization.

211223261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 20.

The square root of 211223261 is about 14533.5219750754. The cubic root of 211223261 is about 595.5440834509.

Adding to 211223261 its reverse (162322112), we get a palindrome (373545373).

It can be divided in two parts, 211 and 223261, that multiplied together give a triangular number (47108071 = T₉₇₀₆).

The spelling of 211223261 in words is "two hundred eleven million, two hundred twenty-three thousand, two hundred sixty-one".