21022222021 has 2 divisors, whose sum is σ = 21022222022. Its totient is φ = 21022222020.

The previous prime is 21022222007. The next prime is 21022222027. The reversal of 21022222021 is 12022222012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17167550625 + 3854671396 = 131025^2 + 62086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022222021 - 2⁷ = 21022221893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21022221986 and 21022222004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21022222027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511111010 + 10511111011.

It is an arithmetic number, because the mean of its divisors is an integer number (10511111011).

Almost surely, 2^21022222021 is an apocalyptic number.

It is an amenable number.

21022222021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022222021 is an equidigital number, since it uses as much as digits as its factorization.

21022222021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21022222021 its reverse (12022222012), we get a palindrome (33044444033).

Subtracting from 21022222021 its reverse (12022222012), we obtain a palindrome (9000000009).

The spelling of 21022222021 in words is "twenty-one billion, twenty-two million, two hundred twenty-two thousand, twenty-one".