9990221 has 2 divisors, whose sum is σ = 9990222. Its totient is φ = 9990220.

The previous prime is 9990209. The next prime is 9990251. The reversal of 9990221 is 1220999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9853321 + 136900 = 3139^2 + 370^2 .

It is a cyclic number.

It is not a de Polignac number, because 9990221 - 2¹⁰ = 9989197 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9990251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995110 + 4995111.

It is an arithmetic number, because the mean of its divisors is an integer number (4995111).

Almost surely, 2^9990221 is an apocalyptic number.

It is an amenable number.

9990221 is a deficient number, since it is larger than the sum of its proper divisors (1).

9990221 is an equidigital number, since it uses as much as digits as its factorization.

9990221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 9990221 is about 3160.7310863153. The cubic root of 9990221 is about 215.3732187095.

The spelling of 9990221 in words is "nine million, nine hundred ninety thousand, two hundred twenty-one".