21202112020021 has 4 divisors (see below), whose sum is σ = 21202340906700. Its totient is φ = 21201883133344.

The previous prime is 21202112020013. The next prime is 21202112020043. The reversal of 21202112020021 is 12002021120212.

It is a happy number.

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 5221745992996 + 15980366027025 = 2285114^2 + 3997545^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202112020021 - 2³ = 21202112020013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202112019977 and 21202112020004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202112020081) 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, 114304336 + ... + 114489673.

It is an arithmetic number, because the mean of its divisors is an integer number (5300585226675).

Almost surely, 2^{21202112020021} is an apocalyptic number.

It is an amenable number.

21202112020021 is a deficient number, since it is larger than the sum of its proper divisors (228886679).

21202112020021 is an equidigital number, since it uses as much as digits as its factorization.

21202112020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228886678.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21202112020021 its reverse (12002021120212), we get a palindrome (33204133140233).

The spelling of 21202112020021 in words is "twenty-one trillion, two hundred two billion, one hundred twelve million, twenty thousand, twenty-one".