9911221 has 4 divisors (see below), whose sum is σ = 10494252. Its totient is φ = 9328192.

The previous prime is 9911201. The next prime is 9911249. The reversal of 9911221 is 1221199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1221199 = 7 ⋅174457.

It can be written as a sum of positive squares in 2 ways, for example, as 6320196 + 3591025 = 2514^2 + 1895^2 .

It is a cyclic number.

It is not a de Polignac number, because 9911221 - 2¹⁷ = 9780149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9911201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 291490 + ... + 291523.

It is an arithmetic number, because the mean of its divisors is an integer number (2623563).

Almost surely, 2^9911221 is an apocalyptic number.

It is an amenable number.

9911221 is a deficient number, since it is larger than the sum of its proper divisors (583031).

9911221 is a wasteful number, since it uses less digits than its factorization.

9911221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583030.

The product of its digits is 324, while the sum is 25.

The square root of 9911221 is about 3148.2091734826. The cubic root of 9911221 is about 214.8040110474.

The spelling of 9911221 in words is "nine million, nine hundred eleven thousand, two hundred twenty-one".