21211110121021 has 4 divisors (see below), whose sum is σ = 21233747379292. Its totient is φ = 21188472862752.

The previous prime is 21211110121001. The next prime is 21211110121031. The reversal of 21211110121021 is 12012101111212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11602436875225 + 9608673245796 = 3406235^2 + 3099786^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211110121021 - 2²⁹ = 21210573250109 is a prime.

It is a super-2 number, since 2×21211110121021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211110120986 and 21211110121004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211110121001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11318627730 + ... + 11318629603.

It is an arithmetic number, because the mean of its divisors is an integer number (5308436844823).

Almost surely, 2^{21211110121021} is an apocalyptic number.

It is an amenable number.

21211110121021 is a deficient number, since it is larger than the sum of its proper divisors (22637258271).

21211110121021 is an equidigital number, since it uses as much as digits as its factorization.

21211110121021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22637258270.

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

Adding to 21211110121021 its reverse (12012101111212), we get a palindrome (33223211232233).

The spelling of 21211110121021 in words is "twenty-one trillion, two hundred eleven billion, one hundred ten million, one hundred twenty-one thousand, twenty-one".