8821 has 2 divisors, whose sum is σ = 8822.
Its totient is φ = 8820.
The previous prime is 8819. The next prime is 8831. The reversal of 8821 is 1288.
It is a happy number.
8821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 7921 + 900 = 89^2 + 30^2
It is a cyclic number.
It is not a de Polignac number, because 8821 - 21 = 8819 is a prime.
Together with 8819, it forms a pair of twin primes.
It is a magnanimous number.
It is equal to p1099 and since 8821 and 1099 have the same sum of digits, it is a Honaker prime.
It is a plaindrome in base 11.
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 (8831) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4410 + 4411.
It is an arithmetic number, because the mean of its divisors is an integer number (4411).
28821 is an apocalyptic number.
It is an amenable number.
8821 is a deficient number, since it is larger than the sum of its proper divisors (1).
8821 is an equidigital number, since it uses as much as digits as its factorization.
8821 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 128, while the sum is 19.
The square root of 8821 is about 93.9201788755.
The cubic root of 8821 is about 20.6620119012.
The spelling of 8821 in words is "eight thousand, eight hundred twenty-one".