21221112212121 has 24 divisors (see below), whose sum is σ = 28543842948096. Its totient is φ = 14023882265760.

The previous prime is 21221112212119. The next prime is 21221112212159. The reversal of 21221112212121 is 12121221112212.

It is not a de Polignac number, because 21221112212121 - 2¹ = 21221112212119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221112212161) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30180211 + ... + 30875351.

It is an arithmetic number, because the mean of its divisors is an integer number (1189326789504).

Almost surely, 2^{21221112212121} is an apocalyptic number.

It is an amenable number.

21221112212121 is a deficient number, since it is larger than the sum of its proper divisors (7322730735975).

21221112212121 is an equidigital number, since it uses as much as digits as its factorization.

21221112212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695853 (or 695690 counting only the distinct ones).

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

Adding to 21221112212121 its reverse (12121221112212), we get a palindrome (33342333324333).

It can be divided in two parts, 21221112212 and 121, that multiplied together give a palindrome (2567754577652).

The spelling of 21221112212121 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred twelve million, two hundred twelve thousand, one hundred twenty-one".