21421444243 has 4 divisors (see below), whose sum is σ = 22352811408. Its totient is φ = 20490077080.

The previous prime is 21421444241. The next prime is 21421444249. The reversal of 21421444243 is 34244412412.

It is a happy number.

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 21421444243 - 2¹ = 21421444241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21421444241) 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, 465683548 + ... + 465683593.

It is an arithmetic number, because the mean of its divisors is an integer number (5588202852).

Almost surely, 2^21421444243 is an apocalyptic number.

21421444243 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21421444243 is a deficient number, since it is larger than the sum of its proper divisors (931367165).

21421444243 is an equidigital number, since it uses as much as digits as its factorization.

21421444243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 931367164.

The product of its digits is 24576, while the sum is 31.

Adding to 21421444243 its reverse (34244412412), we get a palindrome (55665856655).

The spelling of 21421444243 in words is "twenty-one billion, four hundred twenty-one million, four hundred forty-four thousand, two hundred forty-three".