221071891 has 2 divisors, whose sum is σ = 221071892. Its totient is φ = 221071890.

The previous prime is 221071889. The next prime is 221071933. The reversal of 221071891 is 198170122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221071891 - 2¹ = 221071889 is a prime.

Together with 221071889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (221071811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110535945 + 110535946.

It is an arithmetic number, because the mean of its divisors is an integer number (110535946).

Almost surely, 2^221071891 is an apocalyptic number.

221071891 is a deficient number, since it is larger than the sum of its proper divisors (1).

221071891 is an equidigital number, since it uses as much as digits as its factorization.

221071891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 221071891 is about 14868.4865067027. The cubic root of 221071891 is about 604.6599104021.

The spelling of 221071891 in words is "two hundred twenty-one million, seventy-one thousand, eight hundred ninety-one".