20211020021 has 2 divisors, whose sum is σ = 20211020022. Its totient is φ = 20211020020.

The previous prime is 20211019991. The next prime is 20211020033. The reversal of 20211020021 is 12002011202.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19759924900 + 451095121 = 140570^2 + 21239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20211020021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20211019984 and 20211020011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20211020051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105510010 + 10105510011.

It is an arithmetic number, because the mean of its divisors is an integer number (10105510011).

Almost surely, 2^20211020021 is an apocalyptic number.

It is an amenable number.

20211020021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211020021 is an equidigital number, since it uses as much as digits as its factorization.

20211020021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 20211020021 its reverse (12002011202), we get a palindrome (32213031223).

The spelling of 20211020021 in words is "twenty billion, two hundred eleven million, twenty thousand, twenty-one".