21212212212121 has 16 divisors (see below), whose sum is σ = 24806500178944. Its totient is φ = 17758923782544.

The previous prime is 21212212212067. The next prime is 21212212212127. The reversal of 21212212212121 is 12121221221212.

It is not a de Polignac number, because 21212212212121 - 2¹¹ = 21212212210073 is a prime.

It is a super-3 number, since 3×21212212212121³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212212212092 and 21212212212101.

It is not an unprimeable number, because it can be changed into a prime (21212212212127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62808916 + ... + 63145738.

It is an arithmetic number, because the mean of its divisors is an integer number (1550406261184).

Almost surely, 2^{21212212212121} is an apocalyptic number.

It is an amenable number.

21212212212121 is a deficient number, since it is larger than the sum of its proper divisors (3594287966823).

21212212212121 is a wasteful number, since it uses less digits than its factorization.

21212212212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546100.

The product of its digits is 256, while the sum is 22.

Adding to 21212212212121 its reverse (12121221221212), we get a palindrome (33333433433333).

Subtracting from 21212212212121 its reverse (12121221221212), we obtain a palindrome (9090990990909).

The spelling of 21212212212121 in words is "twenty-one trillion, two hundred twelve billion, two hundred twelve million, two hundred twelve thousand, one hundred twenty-one".