21221221112121 has 32 divisors (see below), whose sum is σ = 28704973068288. Its totient is φ = 13944022297920.

The previous prime is 21221221112093. The next prime is 21221221112167. The reversal of 21221221112121 is 12121112212212.

It is not a de Polignac number, because 21221221112121 - 2⁵ = 21221221112089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221221112171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 144738976 + ... + 144885518.

It is an arithmetic number, because the mean of its divisors is an integer number (897030408384).

Almost surely, 2^{21221221112121} is an apocalyptic number.

It is an amenable number.

21221221112121 is a deficient number, since it is larger than the sum of its proper divisors (7483751956167).

21221221112121 is a wasteful number, since it uses less digits than its factorization.

21221221112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149181.

The product of its digits is 128, while the sum is 21.

Adding to 21221221112121 its reverse (12121112212212), we get a palindrome (33342333324333).

The spelling of 21221221112121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-one million, one hundred twelve thousand, one hundred twenty-one".