21043320443 has 4 divisors (see below), whose sum is σ = 22281162840. Its totient is φ = 19805478048.

The previous prime is 21043320437. The next prime is 21043320449. The reversal of 21043320443 is 34402334012.

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

It is an interprime number because it is at equal distance from previous prime (21043320437) and next prime (21043320449).

It is a cyclic number.

It is not a de Polignac number, because 21043320443 - 2⁴ = 21043320427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21043320449) 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, 618921173 + ... + 618921206.

It is an arithmetic number, because the mean of its divisors is an integer number (5570290710).

Almost surely, 2^21043320443 is an apocalyptic number.

21043320443 is a deficient number, since it is larger than the sum of its proper divisors (1237842397).

21043320443 is a wasteful number, since it uses less digits than its factorization.

21043320443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1237842396.

The product of its (nonzero) digits is 6912, while the sum is 26.

Adding to 21043320443 its reverse (34402334012), we get a palindrome (55445654455).

The spelling of 21043320443 in words is "twenty-one billion, forty-three million, three hundred twenty thousand, four hundred forty-three".