9923821 has 2 divisors, whose sum is σ = 9923822. Its totient is φ = 9923820.

The previous prime is 9923819. The next prime is 9923831. The reversal of 9923821 is 1283299.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6734025 + 3189796 = 2595^2 + 1786^2 .

It is a cyclic number.

It is not a de Polignac number, because 9923821 - 2¹ = 9923819 is a prime.

Together with 9923819, 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 (9923831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4961910 + 4961911.

It is an arithmetic number, because the mean of its divisors is an integer number (4961911).

Almost surely, 2^9923821 is an apocalyptic number.

It is an amenable number.

9923821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9923821 is an equidigital number, since it uses as much as digits as its factorization.

9923821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 9923821 is about 3150.2096755613. The cubic root of 9923821 is about 214.8949983040.

The spelling of 9923821 in words is "nine million, nine hundred twenty-three thousand, eight hundred twenty-one".