221101212221 has 2 divisors, whose sum is σ = 221101212222. Its totient is φ = 221101212220.

The previous prime is 221101212191. The next prime is 221101212223. The reversal of 221101212221 is 122212101122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 197304756100 + 23796456121 = 444190^2 + 154261^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221101212221 is a prime.

Together with 221101212223, 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 221101212221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221101212223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110550606110 + 110550606111.

It is an arithmetic number, because the mean of its divisors is an integer number (110550606111).

Almost surely, 2^221101212221 is an apocalyptic number.

It is an amenable number.

221101212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

221101212221 is an equidigital number, since it uses as much as digits as its factorization.

221101212221 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 221101212221 its reverse (122212101122), we get a palindrome (343313313343).

The spelling of 221101212221 in words is "two hundred twenty-one billion, one hundred one million, two hundred twelve thousand, two hundred twenty-one".