8663821 has 2 divisors, whose sum is σ = 8663822. Its totient is φ = 8663820.

The previous prime is 8663819. The next prime is 8663827. The reversal of 8663821 is 1283668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5904900 + 2758921 = 2430^2 + 1661^2 .

It is a cyclic number.

It is not a de Polignac number, because 8663821 - 2¹ = 8663819 is a prime.

Together with 8663819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8663827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4331910 + 4331911.

It is an arithmetic number, because the mean of its divisors is an integer number (4331911).

Almost surely, 2^8663821 is an apocalyptic number.

It is an amenable number.

8663821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8663821 is an equidigital number, since it uses as much as digits as its factorization.

8663821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 34.

The square root of 8663821 is about 2943.4369366440. The cubic root of 8663821 is about 205.3855208211.

The spelling of 8663821 in words is "eight million, six hundred sixty-three thousand, eight hundred twenty-one".