21211020110021 has 12 divisors (see below), whose sum is σ = 24688167566688. Its totient is φ = 18170467395192.

The previous prime is 21211020109943. The next prime is 21211020110047. The reversal of 21211020110021 is 12001102011212.

It is a de Polignac number, because none of the positive numbers 2^k-21211020110021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211020109978 and 21211020110005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211020118021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 123806201 + ... + 123977406.

It is an arithmetic number, because the mean of its divisors is an integer number (2057347297224).

Almost surely, 2^{21211020110021} is an apocalyptic number.

It is an amenable number.

21211020110021 is a deficient number, since it is larger than the sum of its proper divisors (3477147456667).

21211020110021 is a wasteful number, since it uses less digits than its factorization.

21211020110021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247785368 (or 247785361 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21211020110021 its reverse (12001102011212), we get a palindrome (33212122121233).

The spelling of 21211020110021 in words is "twenty-one trillion, two hundred eleven billion, twenty million, one hundred ten thousand, twenty-one".