21031043243 has 4 divisors (see below), whose sum is σ = 24035478000. Its totient is φ = 18026608488.

The previous prime is 21031043233. The next prime is 21031043269. The reversal of 21031043243 is 34234013012.

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

It is not a de Polignac number, because 21031043243 - 2³² = 16736075947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21031043233) 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, 1502217368 + ... + 1502217381.

It is an arithmetic number, because the mean of its divisors is an integer number (6008869500).

Almost surely, 2^21031043243 is an apocalyptic number.

21031043243 is a deficient number, since it is larger than the sum of its proper divisors (3004434757).

21031043243 is an equidigital number, since it uses as much as digits as its factorization.

21031043243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3004434756.

The product of its (nonzero) digits is 1728, while the sum is 23.

Adding to 21031043243 its reverse (34234013012), we get a palindrome (55265056255).

The spelling of 21031043243 in words is "twenty-one billion, thirty-one million, forty-three thousand, two hundred forty-three".