21210002201221 has 16 divisors (see below), whose sum is σ = 22060682780400. Its totient is φ = 20367349746688.

The previous prime is 21210002201173. The next prime is 21210002201237. The reversal of 21210002201221 is 12210220001212.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 6697795760100 + 14512206441121 = 2588010^2 + 3809489^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210002201221 - 2³¹ = 21207854717573 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210002201195 and 21210002201204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210002201261) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15267981 + ... + 16599133.

It is an arithmetic number, because the mean of its divisors is an integer number (1378792673775).

Almost surely, 2^{21210002201221} is an apocalyptic number.

It is an amenable number.

21210002201221 is a deficient number, since it is larger than the sum of its proper divisors (850680579179).

21210002201221 is a wasteful number, since it uses less digits than its factorization.

21210002201221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1334168.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21210002201221 its reverse (12210220001212), we get a palindrome (33420222202433).

The spelling of 21210002201221 in words is "twenty-one trillion, two hundred ten billion, two million, two hundred one thousand, two hundred twenty-one".