21013112321 has 4 divisors (see below), whose sum is σ = 21134575572. Its totient is φ = 20891649072.

The previous prime is 21013112249. The next prime is 21013112353. The reversal of 21013112321 is 12321131012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12401272321 + 8611840000 = 111361^2 + 92800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013112321 - 2¹⁰ = 21013111297 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 21013112321.

It is not an unprimeable number, because it can be changed into a prime (21013112821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60731366 + ... + 60731711.

It is an arithmetic number, because the mean of its divisors is an integer number (5283643893).

Almost surely, 2^21013112321 is an apocalyptic number.

It is an amenable number.

21013112321 is a deficient number, since it is larger than the sum of its proper divisors (121463251).

21013112321 is a wasteful number, since it uses less digits than its factorization.

21013112321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121463250.

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

Adding to 21013112321 its reverse (12321131012), we get a palindrome (33334243333).

The spelling of 21013112321 in words is "twenty-one billion, thirteen million, one hundred twelve thousand, three hundred twenty-one".