21002121120221 has 2 divisors, whose sum is σ = 21002121120222. Its totient is φ = 21002121120220.

The previous prime is 21002121120203. The next prime is 21002121120229. The reversal of 21002121120221 is 12202112120012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17646813057721 + 3355308062500 = 4200811^2 + 1831750^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002121120221 - 2¹⁰ = 21002121119197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21002121120221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002121120229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060560110 + 10501060560111.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060560111).

Almost surely, 2^{21002121120221} is an apocalyptic number.

It is an amenable number.

21002121120221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002121120221 is an equidigital number, since it uses as much as digits as its factorization.

21002121120221 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 21002121120221 its reverse (12202112120012), we get a palindrome (33204233240233).

The spelling of 21002121120221 in words is "twenty-one trillion, two billion, one hundred twenty-one million, one hundred twenty thousand, two hundred twenty-one".