21221211212121 has 32 divisors (see below), whose sum is σ = 29274596352000. Its totient is φ = 13659756739200.

The previous prime is 21221211212083. The next prime is 21221211212239. The reversal of 21221211212121 is 12121211212212.

It is not a de Polignac number, because 21221211212121 - 2²² = 21221207017817 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221211212921) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 166676716 + ... + 166803986.

It is an arithmetic number, because the mean of its divisors is an integer number (914831136000).

Almost surely, 2^{21221211212121} is an apocalyptic number.

It is an amenable number.

21221211212121 is a deficient number, since it is larger than the sum of its proper divisors (8053385139879).

21221211212121 is a wasteful number, since it uses less digits than its factorization.

21221211212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131397.

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

Adding to 21221211212121 its reverse (12121211212212), we get a palindrome (33342422424333).

Subtracting from 21221211212121 its reverse (12121211212212), we obtain a palindrome (9099999999909).

The spelling of 21221211212121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred eleven million, two hundred twelve thousand, one hundred twenty-one".