21044042321 has 2 divisors, whose sum is σ = 21044042322. Its totient is φ = 21044042320.

The previous prime is 21044042317. The next prime is 21044042323. The reversal of 21044042321 is 12324044012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10835769025 + 10208273296 = 104095^2 + 101036^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044042321 - 2² = 21044042317 is a prime.

Together with 21044042323, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21044042323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522021160 + 10522021161.

It is an arithmetic number, because the mean of its divisors is an integer number (10522021161).

Almost surely, 2^21044042321 is an apocalyptic number.

It is an amenable number.

21044042321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21044042321 is an equidigital number, since it uses as much as digits as its factorization.

21044042321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 21044042321 its reverse (12324044012), we get a palindrome (33368086333).

The spelling of 21044042321 in words is "twenty-one billion, forty-four million, forty-two thousand, three hundred twenty-one".