221121222221 has 2 divisors, whose sum is σ = 221121222222. Its totient is φ = 221121222220.

The previous prime is 221121222173. The next prime is 221121222239. The reversal of 221121222221 is 122222121122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 142729062025 + 78392160196 = 377795^2 + 279986^2 .

It is a cyclic number.

It is not a de Polignac number, because 221121222221 - 2¹⁸ = 221120960077 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221121222193 and 221121222202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221121222241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110560611110 + 110560611111.

It is an arithmetic number, because the mean of its divisors is an integer number (110560611111).

Almost surely, 2^221121222221 is an apocalyptic number.

It is an amenable number.

221121222221 is a deficient number, since it is larger than the sum of its proper divisors (1).

221121222221 is an equidigital number, since it uses as much as digits as its factorization.

221121222221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 256, while the sum is 20.

Adding to 221121222221 its reverse (122222121122), we get a palindrome (343343343343).

The spelling of 221121222221 in words is "two hundred twenty-one billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".