21121102221 has 16 divisors (see below), whose sum is σ = 29683184640. Its totient is φ = 13321854000.

The previous prime is 21121102207. The next prime is 21121102267. The reversal of 21121102221 is 12220112112.

It is not a de Polignac number, because 21121102221 - 2¹¹ = 21121100173 is a prime.

It is a super-2 number, since 2×21121102221² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121102221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121102291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 203895 + ... + 289508.

It is an arithmetic number, because the mean of its divisors is an integer number (1855199040).

Almost surely, 2^21121102221 is an apocalyptic number.

It is an amenable number.

21121102221 is a deficient number, since it is larger than the sum of its proper divisors (8562082419).

21121102221 is a wasteful number, since it uses less digits than its factorization.

21121102221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494176.

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

Adding to 21121102221 its reverse (12220112112), we get a palindrome (33341214333).

The spelling of 21121102221 in words is "twenty-one billion, one hundred twenty-one million, one hundred two thousand, two hundred twenty-one".