21212001202121 has 2 divisors, whose sum is σ = 21212001202122. Its totient is φ = 21212001202120.

The previous prime is 21212001202097. The next prime is 21212001202211. The reversal of 21212001202121 is 12120210021212.

Together with next prime (21212001202211) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14622486532096 + 6589514670025 = 3823936^2 + 2567005^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212001202121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212001202121.

It is not a weakly prime, because it can be changed into another prime (21212001207121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606000601060 + 10606000601061.

It is an arithmetic number, because the mean of its divisors is an integer number (10606000601061).

Almost surely, 2^{21212001202121} is an apocalyptic number.

It is an amenable number.

21212001202121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212001202121 is an equidigital number, since it uses as much as digits as its factorization.

21212001202121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21212001202121 its reverse (12120210021212), we get a palindrome (33332211223333).

The spelling of 21212001202121 in words is "twenty-one trillion, two hundred twelve billion, one million, two hundred two thousand, one hundred twenty-one".