21122121012121 has 2 divisors, whose sum is σ = 21122121012122. Its totient is φ = 21122121012120.

The previous prime is 21122121012119. The next prime is 21122121012203. The reversal of 21122121012121 is 12121012122112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16325123070096 + 4796997942025 = 4040436^2 + 2190205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122121012121 - 2¹ = 21122121012119 is a prime.

It is a super-2 number, since 2×21122121012121² (a number of 27 digits) contains 22 as substring.

Together with 21122121012119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21122121012101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561060506060 + 10561060506061.

It is an arithmetic number, because the mean of its divisors is an integer number (10561060506061).

Almost surely, 2^{21122121012121} is an apocalyptic number.

It is an amenable number.

21122121012121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122121012121 is an equidigital number, since it uses as much as digits as its factorization.

21122121012121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21122121012121 its reverse (12121012122112), we get a palindrome (33243133134233).

The spelling of 21122121012121 in words is "twenty-one trillion, one hundred twenty-two billion, one hundred twenty-one million, twelve thousand, one hundred twenty-one".