21201202221021 has 24 divisors (see below), whose sum is σ = 33301729411704. Its totient is φ = 12943182274560.

The previous prime is 21201202221007. The next prime is 21201202221041. The reversal of 21201202221021 is 12012220210212.

It is a happy number.

21201202221021 is a `hidden beast` number, since 21 + 201 + 202 + 221 + 0 + 21 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 9420786648900 + 11780415572121 = 3069330^2 + 3432261^2 .

It is not a de Polignac number, because 21201202221021 - 2⁷ = 21201202220893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201202220985 and 21201202221003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201202221041) 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, 1872561220 + ... + 1872572541.

It is an arithmetic number, because the mean of its divisors is an integer number (1387572058821).

Almost surely, 2^{21201202221021} is an apocalyptic number.

It is an amenable number.

21201202221021 is a deficient number, since it is larger than the sum of its proper divisors (12100527190683).

21201202221021 is a wasteful number, since it uses less digits than its factorization.

21201202221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3745133821 (or 3745133818 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21201202221021 its reverse (12012220210212), we get a palindrome (33213422431233).

The spelling of 21201202221021 in words is "twenty-one trillion, two hundred one billion, two hundred two million, two hundred twenty-one thousand, twenty-one".