21002121012221 has 2 divisors, whose sum is σ = 21002121012222. Its totient is φ = 21002121012220.

The previous prime is 21002121012203. The next prime is 21002121012233. The reversal of 21002121012221 is 12221012120012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20748116100100 + 254004912121 = 4555010^2 + 503989^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002121012221 - 2²² = 21002116817917 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21002121012221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002121012421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060506110 + 10501060506111.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060506111).

Almost surely, 2^{21002121012221} is an apocalyptic number.

It is an amenable number.

21002121012221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002121012221 is an equidigital number, since it uses as much as digits as its factorization.

21002121012221 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 21002121012221 its reverse (12221012120012), we get a palindrome (33223133132233).

The spelling of 21002121012221 in words is "twenty-one trillion, two billion, one hundred twenty-one million, twelve thousand, two hundred twenty-one".