21210201221 has 16 divisors (see below), whose sum is σ = 24520104000. Its totient is φ = 18163017600.

The previous prime is 21210201217. The next prime is 21210201241. The reversal of 21210201221 is 12210201212.

It is a cyclic number.

It is not a de Polignac number, because 21210201221 - 2² = 21210201217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21210201196 and 21210201205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210201241) 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, 797771 + ... + 823928.

It is an arithmetic number, because the mean of its divisors is an integer number (1532506500).

Almost surely, 2^21210201221 is an apocalyptic number.

It is an amenable number.

21210201221 is a deficient number, since it is larger than the sum of its proper divisors (3309902779).

21210201221 is a wasteful number, since it uses less digits than its factorization.

21210201221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621780.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21210201221 its reverse (12210201212), we get a palindrome (33420402433).

Subtracting from 21210201221 its reverse (12210201212), we obtain a palindrome (9000000009).

The spelling of 21210201221 in words is "twenty-one billion, two hundred ten million, two hundred one thousand, two hundred twenty-one".