9825821 has 2 divisors, whose sum is σ = 9825822. Its totient is φ = 9825820.

The previous prime is 9825817. The next prime is 9825833. The reversal of 9825821 is 1285289.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8637721 + 1188100 = 2939^2 + 1090^2 .

It is an emirp because it is prime and its reverse (1285289) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9825821 - 2² = 9825817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9825841) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4912910 + 4912911.

It is an arithmetic number, because the mean of its divisors is an integer number (4912911).

Almost surely, 2^9825821 is an apocalyptic number.

It is an amenable number.

9825821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9825821 is an equidigital number, since it uses as much as digits as its factorization.

9825821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 35.

The square root of 9825821 is about 3134.6165634731. The cubic root of 9825821 is about 214.1852778637.

The spelling of 9825821 in words is "nine million, eight hundred twenty-five thousand, eight hundred twenty-one".