221211201221 has 2 divisors, whose sum is σ = 221211201222. Its totient is φ = 221211201220.

The previous prime is 221211201209. The next prime is 221211201223. The reversal of 221211201221 is 122102112122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 150108978721 + 71102222500 = 387439^2 + 266650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221211201221 is a prime.

Together with 221211201223, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221211201221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221211201223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110605600610 + 110605600611.

It is an arithmetic number, because the mean of its divisors is an integer number (110605600611).

Almost surely, 2^221211201221 is an apocalyptic number.

It is an amenable number.

221211201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

221211201221 is an equidigital number, since it uses as much as digits as its factorization.

221211201221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 221211201221 its reverse (122102112122), we get a palindrome (343313313343).

The spelling of 221211201221 in words is "two hundred twenty-one billion, two hundred eleven million, two hundred one thousand, two hundred twenty-one".