21121221000221 has 2 divisors, whose sum is σ = 21121221000222. Its totient is φ = 21121221000220.

The previous prime is 21121221000161. The next prime is 21121221000239. The reversal of 21121221000221 is 12200012212112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21043449734596 + 77771265625 = 4587314^2 + 278875^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121221000221 - 2³⁴ = 21104041131037 is a prime.

It is a super-2 number, since 2×21121221000221² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21121221000221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121221000281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560610500110 + 10560610500111.

It is an arithmetic number, because the mean of its divisors is an integer number (10560610500111).

Almost surely, 2^{21121221000221} is an apocalyptic number.

It is an amenable number.

21121221000221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121221000221 is an equidigital number, since it uses as much as digits as its factorization.

21121221000221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21121221000221 its reverse (12200012212112), we get a palindrome (33321233212333).

The spelling of 21121221000221 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty-one million, two hundred twenty-one", and thus it is an aban number.