9861821 has 2 divisors, whose sum is σ = 9861822. Its totient is φ = 9861820.

The previous prime is 9861781. The next prime is 9861833. The reversal of 9861821 is 1281689.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9424900 + 436921 = 3070^2 + 661^2 .

It is a cyclic number.

It is not a de Polignac number, because 9861821 - 2⁶ = 9861757 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9861881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4930910 + 4930911.

It is an arithmetic number, because the mean of its divisors is an integer number (4930911).

Almost surely, 2^9861821 is an apocalyptic number.

It is an amenable number.

9861821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9861821 is an equidigital number, since it uses as much as digits as its factorization.

9861821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 35.

The square root of 9861821 is about 3140.3536425059. The cubic root of 9861821 is about 214.4465375351.

The spelling of 9861821 in words is "nine million, eight hundred sixty-one thousand, eight hundred twenty-one".