21021021211221 has 24 divisors (see below), whose sum is σ = 30585878570520. Its totient is φ = 13911841161216.

The previous prime is 21021021211199. The next prime is 21021021211231. The reversal of 21021021211221 is 12211212012012.

21021021211221 is a `hidden beast` number, since 2 + 1 + 0 + 210 + 21 + 211 + 221 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 17419262502321 + 3601758708900 = 4173639^2 + 1897830^2 .

It is not a de Polignac number, because 21021021211221 - 2¹¹ = 21021021209173 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021021211194 and 21021021211203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021021211231) 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 in 23 ways as a sum of consecutive naturals, for example, 14831176 + ... + 16186593.

It is an arithmetic number, because the mean of its divisors is an integer number (1274411607105).

Almost surely, 2^{21021021211221} is an apocalyptic number.

It is an amenable number.

21021021211221 is a deficient number, since it is larger than the sum of its proper divisors (9564857359299).

21021021211221 is a wasteful number, since it uses less digits than its factorization.

21021021211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31018325 (or 31018322 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21021021211221 its reverse (12211212012012), we get a palindrome (33232233223233).

The spelling of 21021021211221 in words is "twenty-one trillion, twenty-one billion, twenty-one million, two hundred eleven thousand, two hundred twenty-one".