21210110001221 has 8 divisors (see below), whose sum is σ = 21420364512504. Its totient is φ = 20999860459200.

The previous prime is 21210110001193. The next prime is 21210110001229. The reversal of 21210110001221 is 12210001101212.

It can be written as a sum of positive squares in 4 ways, for example, as 16755604276321 + 4454505724900 = 4093361^2 + 2110570^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21210110001221 - 2¹⁰ = 21210110000197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210110001196 and 21210110001205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210110001229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7650455 + ... + 10047371.

It is an arithmetic number, because the mean of its divisors is an integer number (2677545564063).

Almost surely, 2^{21210110001221} is an apocalyptic number.

It is an amenable number.

21210110001221 is a deficient number, since it is larger than the sum of its proper divisors (210254511283).

21210110001221 is a wasteful number, since it uses less digits than its factorization.

21210110001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2484631.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21210110001221 its reverse (12210001101212), we get a palindrome (33420111102433).

The spelling of 21210110001221 in words is "twenty-one trillion, two hundred ten billion, one hundred ten million, one thousand, two hundred twenty-one".