21121021021021 has 2 divisors, whose sum is σ = 21121021021022. Its totient is φ = 21121021021020.

The previous prime is 21121021021019. The next prime is 21121021021043. The reversal of 21121021021021 is 12012012012112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13516939018521 + 7604082002500 = 3676539^2 + 2757550^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121021021021 - 2¹ = 21121021021019 is a prime.

Together with 21121021021019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21121021020986 and 21121021021004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121021021621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560510510510 + 10560510510511.

It is an arithmetic number, because the mean of its divisors is an integer number (10560510510511).

Almost surely, 2^{21121021021021} is an apocalyptic number.

It is an amenable number.

21121021021021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121021021021 is an equidigital number, since it uses as much as digits as its factorization.

21121021021021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21121021021021 its reverse (12012012012112), we get a palindrome (33133033033133).

The spelling of 21121021021021 in words is "twenty-one trillion, one hundred twenty-one billion, twenty-one million, twenty-one thousand, twenty-one".