8221 has 2 divisors, whose sum is σ = 8222.
Its totient is φ = 8220.
The previous prime is 8219. The next prime is 8231. The reversal of 8221 is 1228.
Adding to 8221 its reverse (1228), we get a palindrome (9449).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 8100 + 121 = 90^2 + 11^2
It is a cyclic number.
It is not a de Polignac number, because 8221 - 21 = 8219 is a prime.
Together with 8219, it forms a pair of twin primes.
It is a Chen prime.
It is a magnanimous number.
8221 is a lucky number.
It is a plaindrome in base 9.
It is a nialpdrome in base 10.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (8231) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4110 + 4111.
It is an arithmetic number, because the mean of its divisors is an integer number (4111).
28221 is an apocalyptic number.
It is an amenable number.
8221 is a deficient number, since it is larger than the sum of its proper divisors (1).
8221 is an equidigital number, since it uses as much as digits as its factorization.
8221 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 32, while the sum is 13.
The square root of 8221 is about 90.6697303404.
The cubic root of 8221 is about 20.1824963557.
The spelling of 8221 in words is "eight thousand, two hundred twenty-one".