21002212121221 has 2 divisors, whose sum is σ = 21002212121222. Its totient is φ = 21002212121220.

The previous prime is 21002212121203. The next prime is 21002212121227. The reversal of 21002212121221 is 12212121220012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19172926116100 + 1829286005121 = 4378690^2 + 1352511^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002212121221 - 2¹⁵ = 21002212088453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002212121227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501106060610 + 10501106060611.

It is an arithmetic number, because the mean of its divisors is an integer number (10501106060611).

Almost surely, 2^{21002212121221} is an apocalyptic number.

It is an amenable number.

21002212121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002212121221 is an equidigital number, since it uses as much as digits as its factorization.

21002212121221 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 19.

Adding to 21002212121221 its reverse (12212121220012), we get a palindrome (33214333341233).

The spelling of 21002212121221 in words is "twenty-one trillion, two billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twenty-one".