9875821 has 2 divisors, whose sum is σ = 9875822. Its totient is φ = 9875820.

The previous prime is 9875813. The next prime is 9875893. The reversal of 9875821 is 1285789.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9853321 + 22500 = 3139^2 + 150^2 .

It is an emirp because it is prime and its reverse (1285789) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9875821 - 2³ = 9875813 is a prime.

9875821 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9875321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4937910 + 4937911.

It is an arithmetic number, because the mean of its divisors is an integer number (4937911).

Almost surely, 2^9875821 is an apocalyptic number.

It is an amenable number.

9875821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9875821 is an equidigital number, since it uses as much as digits as its factorization.

9875821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 40.

The square root of 9875821 is about 3142.5819002852. The cubic root of 9875821 is about 214.5479668068.

The spelling of 9875821 in words is "nine million, eight hundred seventy-five thousand, eight hundred twenty-one".