21221001222121 has 2 divisors, whose sum is σ = 21221001222122. Its totient is φ = 21221001222120.

The previous prime is 21221001222079. The next prime is 21221001222139. The reversal of 21221001222121 is 12122210012212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11963221346521 + 9257779875600 = 3458789^2 + 3042660^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221001222121 - 2⁴¹ = 19021977966569 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221001222191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610500611060 + 10610500611061.

It is an arithmetic number, because the mean of its divisors is an integer number (10610500611061).

Almost surely, 2^{21221001222121} is an apocalyptic number.

It is an amenable number.

21221001222121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221001222121 is an equidigital number, since it uses as much as digits as its factorization.

21221001222121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21221001222121 its reverse (12122210012212), we get a palindrome (33343211234333).

The spelling of 21221001222121 in words is "twenty-one trillion, two hundred twenty-one billion, one million, two hundred twenty-two thousand, one hundred twenty-one".