221891 has 2 divisors, whose sum is σ = 221892. Its totient is φ = 221890.

The previous prime is 221873. The next prime is 221909. The reversal of 221891 is 198122.

221891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (221873) and next prime (221909).

It is a cyclic number.

It is not a de Polignac number, because 221891 - 2⁶ = 221827 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110945 + 110946.

It is an arithmetic number, because the mean of its divisors is an integer number (110946).

2²²¹⁸⁹¹ is an apocalyptic number.

221891 is a deficient number, since it is larger than the sum of its proper divisors (1).

221891 is an equidigital number, since it uses as much as digits as its factorization.

221891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 23.

The square root of 221891 is about 471.0530755658. The cubic root of 221891 is about 60.5405779278.

The spelling of 221891 in words is "two hundred twenty-one thousand, eight hundred ninety-one".