217442211221 has 2 divisors, whose sum is σ = 217442211222. Its totient is φ = 217442211220.

The previous prime is 217442211211. The next prime is 217442211241. The reversal of 217442211221 is 122112244712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 185360386225 + 32081824996 = 430535^2 + 179114^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217442211221 is a prime.

It is a super-2 number, since 2×217442211221² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217442211211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108721105610 + 108721105611.

It is an arithmetic number, because the mean of its divisors is an integer number (108721105611).

Almost surely, 2^217442211221 is an apocalyptic number.

It is an amenable number.

217442211221 is a deficient number, since it is larger than the sum of its proper divisors (1).

217442211221 is an equidigital number, since it uses as much as digits as its factorization.

217442211221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3584, while the sum is 29.

Adding to 217442211221 its reverse (122112244712), we get a palindrome (339554455933).

The spelling of 217442211221 in words is "two hundred seventeen billion, four hundred forty-two million, two hundred eleven thousand, two hundred twenty-one".