21042442321 has 4 divisors (see below), whose sum is σ = 21087501552. Its totient is φ = 20997383092.

The previous prime is 21042442307. The next prime is 21042442349. The reversal of 21042442321 is 12324424012.

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 21042442321 - 2¹¹ = 21042440273 is a prime.

It is a super-2 number, since 2×21042442321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042442391) 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, 22528915 + ... + 22529848.

It is an arithmetic number, because the mean of its divisors is an integer number (5271875388).

Almost surely, 2^21042442321 is an apocalyptic number.

It is an amenable number.

21042442321 is a deficient number, since it is larger than the sum of its proper divisors (45059231).

21042442321 is an equidigital number, since it uses as much as digits as its factorization.

21042442321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45059230.

The product of its (nonzero) digits is 3072, while the sum is 25.

Adding to 21042442321 its reverse (12324424012), we get a palindrome (33366866333).

The spelling of 21042442321 in words is "twenty-one billion, forty-two million, four hundred forty-two thousand, three hundred twenty-one".