21043320321 has 8 divisors (see below), whose sum is σ = 28078082944. Its totient is φ = 14018718960.

The previous prime is 21043320313. The next prime is 21043320329. The reversal of 21043320321 is 12302334012.

It is an interprime number because it is at equal distance from previous prime (21043320313) and next prime (21043320329).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21043320321 - 2³ = 21043320313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21043320329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2535481 + ... + 2543766.

It is an arithmetic number, because the mean of its divisors is an integer number (3509760368).

Almost surely, 2^21043320321 is an apocalyptic number.

It is an amenable number.

21043320321 is a deficient number, since it is larger than the sum of its proper divisors (7034762623).

21043320321 is a wasteful number, since it uses less digits than its factorization.

21043320321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5080631.

The product of its (nonzero) digits is 864, while the sum is 21.

Adding to 21043320321 its reverse (12302334012), we get a palindrome (33345654333).

The spelling of 21043320321 in words is "twenty-one billion, forty-three million, three hundred twenty thousand, three hundred twenty-one".