10212121021 has 2 divisors, whose sum is σ = 10212121022. Its totient is φ = 10212121020.

The previous prime is 10212121019. The next prime is 10212121057. The reversal of 10212121021 is 12012121201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9038304900 + 1173816121 = 95070^2 + 34261^2 .

It is an emirp because it is prime and its reverse (12012121201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 10212121021 - 2¹ = 10212121019 is a prime.

Together with 10212121019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 10212120992 and 10212121010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (10212121001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5106060510 + 5106060511.

It is an arithmetic number, because the mean of its divisors is an integer number (5106060511).

Almost surely, 2^10212121021 is an apocalyptic number.

It is an amenable number.

10212121021 is a deficient number, since it is larger than the sum of its proper divisors (1).

10212121021 is an equidigital number, since it uses as much as digits as its factorization.

10212121021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 10212121021 its reverse (12012121201), we get a palindrome (22224242222).

The spelling of 10212121021 in words is "ten billion, two hundred twelve million, one hundred twenty-one thousand, twenty-one".