9391212221 has 2 divisors, whose sum is σ = 9391212222. Its totient is φ = 9391212220.

The previous prime is 9391212217. The next prime is 9391212241. The reversal of 9391212221 is 1222121939.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8007744196 + 1383468025 = 89486^2 + 37195^2 .

It is an emirp because it is prime and its reverse (1222121939) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9391212221 - 2² = 9391212217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9391212211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4695606110 + 4695606111.

It is an arithmetic number, because the mean of its divisors is an integer number (4695606111).

Almost surely, 2^9391212221 is an apocalyptic number.

It is an amenable number.

9391212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

9391212221 is an equidigital number, since it uses as much as digits as its factorization.

9391212221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 9391212221 is about 96908.2670415687. The cubic root of 9391212221 is about 2109.7964225623.

The spelling of 9391212221 in words is "nine billion, three hundred ninety-one million, two hundred twelve thousand, two hundred twenty-one".