21211201221 has 32 divisors (see below), whose sum is σ = 32533893120. Its totient is φ = 12041339904.

The previous prime is 21211201139. The next prime is 21211201337. The reversal of 21211201221 is 12210211212.

It is not a de Polignac number, because 21211201221 - 2⁷ = 21211201093 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21211201221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211201421) 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 31 ways as a sum of consecutive naturals, for example, 3332440 + ... + 3338798.

It is an arithmetic number, because the mean of its divisors is an integer number (1016684160).

Almost surely, 2^21211201221 is an apocalyptic number.

21211201221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21211201221 is a deficient number, since it is larger than the sum of its proper divisors (11322691899).

21211201221 is a wasteful number, since it uses less digits than its factorization.

21211201221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7385.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21211201221 its reverse (12210211212), we get a palindrome (33421412433).

Subtracting from 21211201221 its reverse (12210211212), we obtain a palindrome (9000990009).

The spelling of 21211201221 in words is "twenty-one billion, two hundred eleven million, two hundred one thousand, two hundred twenty-one".