8120211221 has 2 divisors, whose sum is σ = 8120211222. Its totient is φ = 8120211220.

The previous prime is 8120211163. The next prime is 8120211227. The reversal of 8120211221 is 1221120218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7363356100 + 756855121 = 85810^2 + 27511^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8120211221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 8120211193 and 8120211202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8120211227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4060105610 + 4060105611.

It is an arithmetic number, because the mean of its divisors is an integer number (4060105611).

Almost surely, 2^8120211221 is an apocalyptic number.

It is an amenable number.

8120211221 is a deficient number, since it is larger than the sum of its proper divisors (1).

8120211221 is an equidigital number, since it uses as much as digits as its factorization.

8120211221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 8120211221 is about 90112.2146049025. The cubic root of 8120211221 is about 2009.9678402980.

Adding to 8120211221 its reverse (1221120218), we get a palindrome (9341331439).

The spelling of 8120211221 in words is "eight billion, one hundred twenty million, two hundred eleven thousand, two hundred twenty-one".