21010211222221 has 16 divisors (see below), whose sum is σ = 22861038208624. Its totient is φ = 19192931057664.

The previous prime is 21010211222183. The next prime is 21010211222251. The reversal of 21010211222221 is 12222211201012.

It can be written as a sum of positive squares in 8 ways, for example, as 11949769225 + 20998261452996 = 109315^2 + 4582386^2 .

It is not a de Polignac number, because 21010211222221 - 2¹⁵ = 21010211189453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010211222251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20504341 + ... + 21504613.

It is an arithmetic number, because the mean of its divisors is an integer number (1428814888039).

Almost surely, 2^{21010211222221} is an apocalyptic number.

It is an amenable number.

21010211222221 is a deficient number, since it is larger than the sum of its proper divisors (1850826986403).

21010211222221 is a wasteful number, since it uses less digits than its factorization.

21010211222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1017040.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21010211222221 its reverse (12222211201012), we get a palindrome (33232422423233).

The spelling of 21010211222221 in words is "twenty-one trillion, ten billion, two hundred eleven million, two hundred twenty-two thousand, two hundred twenty-one".