21023204243 has 4 divisors (see below), whose sum is σ = 21419868528. Its totient is φ = 20626539960.

The previous prime is 21023204201. The next prime is 21023204263. The reversal of 21023204243 is 34240232012.

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 21023204243 - 2⁶ = 21023204179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21023204263) 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, 198332063 + ... + 198332168.

It is an arithmetic number, because the mean of its divisors is an integer number (5354967132).

Almost surely, 2^21023204243 is an apocalyptic number.

21023204243 is a deficient number, since it is larger than the sum of its proper divisors (396664285).

21023204243 is an equidigital number, since it uses as much as digits as its factorization.

21023204243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396664284.

The product of its (nonzero) digits is 2304, while the sum is 23.

Adding to 21023204243 its reverse (34240232012), we get a palindrome (55263436255).

The spelling of 21023204243 in words is "twenty-one billion, twenty-three million, two hundred four thousand, two hundred forty-three".