21204210043 has 4 divisors (see below), whose sum is σ = 21241476360. Its totient is φ = 21166943728.

The previous prime is 21204210023. The next prime is 21204210047. The reversal of 21204210043 is 34001240212.

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

It is a cyclic number.

It is not a de Polignac number, because 21204210043 - 2⁵ = 21204210011 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 21204210043.

It is not an unprimeable number, because it can be changed into a prime (21204210047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18632305 + ... + 18633442.

It is an arithmetic number, because the mean of its divisors is an integer number (5310369090).

Almost surely, 2^21204210043 is an apocalyptic number.

21204210043 is a deficient number, since it is larger than the sum of its proper divisors (37266317).

21204210043 is an equidigital number, since it uses as much as digits as its factorization.

21204210043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37266316.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21204210043 its reverse (34001240212), we get a palindrome (55205450255).

The spelling of 21204210043 in words is "twenty-one billion, two hundred four million, two hundred ten thousand, forty-three".