21010121010121 has 2 divisors, whose sum is σ = 21010121010122. Its totient is φ = 21010121010120.

The previous prime is 21010121010041. The next prime is 21010121010139. The reversal of 21010121010121 is 12101012101012.

It is a happy number.

21010121010121 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20721978579600 + 288142430521 = 4552140^2 + 536789^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010121010121 - 2³³ = 21001531075529 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21010121010191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505060505060 + 10505060505061.

It is an arithmetic number, because the mean of its divisors is an integer number (10505060505061).

Almost surely, 2^{21010121010121} is an apocalyptic number.

It is an amenable number.

21010121010121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010121010121 is an equidigital number, since it uses as much as digits as its factorization.

21010121010121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21010121010121 its reverse (12101012101012), we get a palindrome (33111133111133).

The spelling of 21010121010121 in words is "twenty-one trillion, ten billion, one hundred twenty-one million, ten thousand, one hundred twenty-one".