21020211211221 has 24 divisors (see below), whose sum is σ = 30477034718936. Its totient is φ = 13960676021760.

The previous prime is 21020211211177. The next prime is 21020211211247. The reversal of 21020211211221 is 12211211202012.

21020211211221 is a `hidden beast` number, since 2 + 1 + 0 + 20 + 211 + 211 + 221 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 4188104948196 + 16832106263025 = 2046486^2 + 4102695^2 .

It is not a de Polignac number, because 21020211211221 - 2⁹ = 21020211210709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020211211194 and 21020211211203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020211211921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2761401 + ... + 7047393.

Almost surely, 2^{21020211211221} is an apocalyptic number.

It is an amenable number.

21020211211221 is a deficient number, since it is larger than the sum of its proper divisors (9456823507715).

21020211211221 is a wasteful number, since it uses less digits than its factorization.

21020211211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4288053 (or 4288050 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21020211211221 its reverse (12211211202012), we get a palindrome (33231422413233).

The spelling of 21020211211221 in words is "twenty-one trillion, twenty billion, two hundred eleven million, two hundred eleven thousand, two hundred twenty-one".