11211211220221 has 2 divisors, whose sum is σ = 11211211220222. Its totient is φ = 11211211220220.

The previous prime is 11211211220213. The next prime is 11211211220267. The reversal of 11211211220221 is 12202211211211.

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., 10791454951225 + 419756268996 = 3285035^2 + 647886^2 .

It is a cyclic number.

It is not a de Polignac number, because 11211211220221 - 2³ = 11211211220213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11211211220291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5605605610110 + 5605605610111.

It is an arithmetic number, because the mean of its divisors is an integer number (5605605610111).

Almost surely, 2^{11211211220221} is an apocalyptic number.

It is an amenable number.

11211211220221 is a deficient number, since it is larger than the sum of its proper divisors (1).

11211211220221 is an equidigital number, since it uses as much as digits as its factorization.

11211211220221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 11211211220221 its reverse (12202211211211), we get a palindrome (23413422431432).

The spelling of 11211211220221 in words is "eleven trillion, two hundred eleven billion, two hundred eleven million, two hundred twenty thousand, two hundred twenty-one".