21213412121 has 4 divisors (see below), whose sum is σ = 23141904144. Its totient is φ = 19284920100.

The previous prime is 21213412081. The next prime is 21213412147. The reversal of 21213412121 is 12121431212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21213412121 - 2¹⁴ = 21213395737 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21213412093 and 21213412102.

It is not an unprimeable number, because it can be changed into a prime (21213412321) 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 3 ways as a sum of consecutive naturals, for example, 964245995 + ... + 964246016.

It is an arithmetic number, because the mean of its divisors is an integer number (5785476036).

Almost surely, 2^21213412121 is an apocalyptic number.

It is an amenable number.

21213412121 is a deficient number, since it is larger than the sum of its proper divisors (1928492023).

21213412121 is a wasteful number, since it uses less digits than its factorization.

21213412121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1928492022.

The product of its digits is 192, while the sum is 20.

Adding to 21213412121 its reverse (12121431212), we get a palindrome (33334843333).

It can be divided in two parts, 21213 and 412121, that added together give a palindrome (433334).

The spelling of 21213412121 in words is "twenty-one billion, two hundred thirteen million, four hundred twelve thousand, one hundred twenty-one".