21212202012121 has 2 divisors, whose sum is σ = 21212202012122. Its totient is φ = 21212202012120.

The previous prime is 21212202012119. The next prime is 21212202012179. The reversal of 21212202012121 is 12121020221212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16821769059225 + 4390432952896 = 4101435^2 + 2095336^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212202012121 - 2¹ = 21212202012119 is a prime.

Together with 21212202012119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21212202019121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606101006060 + 10606101006061.

It is an arithmetic number, because the mean of its divisors is an integer number (10606101006061).

Almost surely, 2^{21212202012121} is an apocalyptic number.

It is an amenable number.

21212202012121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212202012121 is an equidigital number, since it uses as much as digits as its factorization.

21212202012121 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 21212202012121 its reverse (12121020221212), we get a palindrome (33333222233333).

The spelling of 21212202012121 in words is "twenty-one trillion, two hundred twelve billion, two hundred two million, twelve thousand, one hundred twenty-one".