211891 has 2 divisors, whose sum is σ = 211892. Its totient is φ = 211890.

The previous prime is 211889. The next prime is 211927. The reversal of 211891 is 198112.

211891 is nontrivially palindromic in base 4.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 211891 - 2¹ = 211889 is a prime.

Together with 211889, it forms a pair of twin primes.

211891 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (211801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105945 + 105946.

It is an arithmetic number, because the mean of its divisors is an integer number (105946).

2²¹¹⁸⁹¹ is an apocalyptic number.

211891 is a deficient number, since it is larger than the sum of its proper divisors (1).

211891 is an equidigital number, since it uses as much as digits as its factorization.

211891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 22.

The square root of 211891 is about 460.3161956742. The cubic root of 211891 is about 59.6170986780.

It can be divided in two parts, 2118 and 91, that added together give a square (2209 = 47²).

The spelling of 211891 in words is "two hundred eleven thousand, eight hundred ninety-one".