21320012121 has 16 divisors (see below), whose sum is σ = 28517185920. Its totient is φ = 14168142720.

The previous prime is 21320012117. The next prime is 21320012123. The reversal of 21320012121 is 12121002312.

It is not a de Polignac number, because 21320012121 - 2² = 21320012117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21320012121.

It is not an unprimeable number, because it can be changed into a prime (21320012123) 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, 1887631 + ... + 1898891.

It is an arithmetic number, because the mean of its divisors is an integer number (1782324120).

Almost surely, 2^21320012121 is an apocalyptic number.

It is an amenable number.

21320012121 is a deficient number, since it is larger than the sum of its proper divisors (7197173799).

21320012121 is a wasteful number, since it uses less digits than its factorization.

21320012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13216.

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21320012121 its reverse (12121002312), we get a palindrome (33441014433).

The spelling of 21320012121 in words is "twenty-one billion, three hundred twenty million, twelve thousand, one hundred twenty-one".