21210120220021 has 16 divisors (see below), whose sum is σ = 21964732433280. Its totient is φ = 20465688795840.

The previous prime is 21210120220007. The next prime is 21210120220063. The reversal of 21210120220021 is 12002202101212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21210120220021 - 2⁵ = 21210120219989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210120219977 and 21210120220004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210120220721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2006791 + ... + 6815236.

It is an arithmetic number, because the mean of its divisors is an integer number (1372795777080).

Almost surely, 2^{21210120220021} is an apocalyptic number.

It is an amenable number.

21210120220021 is a deficient number, since it is larger than the sum of its proper divisors (754612213259).

21210120220021 is a wasteful number, since it uses less digits than its factorization.

21210120220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8822604.

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

Adding to 21210120220021 its reverse (12002202101212), we get a palindrome (33212322321233).

The spelling of 21210120220021 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty million, two hundred twenty thousand, twenty-one".