9999221 has 2 divisors, whose sum is σ = 9999222. Its totient is φ = 9999220.

The previous prime is 9999217. The next prime is 9999233. The reversal of 9999221 is 1229999.

9999221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7562500 + 2436721 = 2750^2 + 1561^2 .

It is an emirp because it is prime and its reverse (1229999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9999221 - 2² = 9999217 is a prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9999271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4999610 + 4999611.

It is an arithmetic number, because the mean of its divisors is an integer number (4999611).

Almost surely, 2^9999221 is an apocalyptic number.

It is an amenable number.

9999221 is a deficient number, since it is larger than the sum of its proper divisors (1).

9999221 is an equidigital number, since it uses as much as digits as its factorization.

9999221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26244, while the sum is 41.

The square root of 9999221 is about 3162.1544870547. The cubic root of 9999221 is about 215.4378745092.

The spelling of 9999221 in words is "nine million, nine hundred ninety-nine thousand, two hundred twenty-one".