7211221021 has 2 divisors, whose sum is σ = 7211221022. Its totient is φ = 7211221020.

The previous prime is 7211221009. The next prime is 7211221037. The reversal of 7211221021 is 1201221127.

7211221021 is digitally balanced in base 3, 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., 5667831225 + 1543389796 = 75285^2 + 39286^2 .

It is an emirp because it is prime and its reverse (1201221127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7211221021 - 2¹³ = 7211212829 is a prime.

It is a super-2 number, since 2×7211221021² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 7211221021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7211221001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3605610510 + 3605610511.

It is an arithmetic number, because the mean of its divisors is an integer number (3605610511).

Almost surely, 2^7211221021 is an apocalyptic number.

It is an amenable number.

7211221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

7211221021 is an equidigital number, since it uses as much as digits as its factorization.

7211221021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 7211221021 is about 84918.9085009929. The cubic root of 7211221021 is about 1931.9813760141.

Adding to 7211221021 its reverse (1201221127), we get a palindrome (8412442148).

The spelling of 7211221021 in words is "seven billion, two hundred eleven million, two hundred twenty-one thousand, twenty-one".