21103312121 has 4 divisors (see below), whose sum is σ = 21104065872. Its totient is φ = 21102558372.

The previous prime is 21103312081. The next prime is 21103312123. The reversal of 21103312121 is 12121330112.

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 a de Polignac number, because none of the positive numbers 2^k-21103312121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21103312121.

It is not an unprimeable number, because it can be changed into a prime (21103312123) 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 3 ways as a sum of consecutive naturals, for example, 333191 + ... + 391436.

It is an arithmetic number, because the mean of its divisors is an integer number (5276016468).

Almost surely, 2^21103312121 is an apocalyptic number.

It is an amenable number.

21103312121 is a deficient number, since it is larger than the sum of its proper divisors (753751).

21103312121 is an equidigital number, since it uses as much as digits as its factorization.

21103312121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 753750.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21103312121 its reverse (12121330112), we get a palindrome (33224642233).

The spelling of 21103312121 in words is "twenty-one billion, one hundred three million, three hundred twelve thousand, one hundred twenty-one".