20021021210221 has 4 divisors (see below), whose sum is σ = 21198728340252. Its totient is φ = 18843314080192.

The previous prime is 20021021210191. The next prime is 20021021210237. The reversal of 20021021210221 is 12201212012002.

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 12125117908996 + 7895903301225 = 3482114^2 + 2809965^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021021210221 - 2¹¹ = 20021021208173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021021210195 and 20021021210204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021021217221) 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, 588853564990 + ... + 588853565023.

It is an arithmetic number, because the mean of its divisors is an integer number (5299682085063).

Almost surely, 2^{20021021210221} is an apocalyptic number.

It is an amenable number.

20021021210221 is a deficient number, since it is larger than the sum of its proper divisors (1177707130031).

20021021210221 is a wasteful number, since it uses less digits than its factorization.

20021021210221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1177707130030.

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

Adding to 20021021210221 its reverse (12201212012002), we get a palindrome (32222233222223).

The spelling of 20021021210221 in words is "twenty trillion, twenty-one billion, twenty-one million, two hundred ten thousand, two hundred twenty-one".