9090821 has 2 divisors, whose sum is σ = 9090822. Its totient is φ = 9090820.

The previous prime is 9090811. The next prime is 9090847. The reversal of 9090821 is 1280909.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5522500 + 3568321 = 2350^2 + 1889^2 .

It is a cyclic number.

It is not a de Polignac number, because 9090821 - 2¹⁴ = 9074437 is a prime.

It is a Sophie Germain 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 (9090811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4545410 + 4545411.

It is an arithmetic number, because the mean of its divisors is an integer number (4545411).

Almost surely, 2^9090821 is an apocalyptic number.

It is an amenable number.

9090821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9090821 is an equidigital number, since it uses as much as digits as its factorization.

9090821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 9090821 is about 3015.0988375176. The cubic root of 9090821 is about 208.7057281185.

The spelling of 9090821 in words is "nine million, ninety thousand, eight hundred twenty-one".