21002000221 has 2 divisors, whose sum is σ = 21002000222. Its totient is φ = 21002000220.

The previous prime is 21002000207. The next prime is 21002000233. The reversal of 21002000221 is 12200020012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14038932196 + 6963068025 = 118486^2 + 83445^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002000221 - 2¹⁵ = 21001967453 is a prime.

It is a super-3 number, since 3×21002000221³ (a number of 32 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21002000198 and 21002000207.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002000251) 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, 10501000110 + 10501000111.

It is an arithmetic number, because the mean of its divisors is an integer number (10501000111).

Almost surely, 2^21002000221 is an apocalyptic number.

It is an amenable number.

21002000221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002000221 is an equidigital number, since it uses as much as digits as its factorization.

21002000221 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 10.

Adding to 21002000221 its reverse (12200020012), we get a palindrome (33202020233).

The spelling of 21002000221 in words is "twenty-one billion, two million, two hundred twenty-one", and thus it is an aban number.