21420243223 has 6 divisors (see below), whose sum is σ = 21622314896. Its totient is φ = 21220042692.

The previous prime is 21420243193. The next prime is 21420243227. The reversal of 21420243223 is 32234202412.

It is a de Polignac number, because none of the positive numbers 2^k-21420243223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420243227) 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 5 ways as a sum of consecutive naturals, for example, 924015 + ... + 946912.

Almost surely, 2^21420243223 is an apocalyptic number.

21420243223 is a deficient number, since it is larger than the sum of its proper divisors (202071673).

21420243223 is an equidigital number, since it uses as much as digits as its factorization.

21420243223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1871141 (or 1871034 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 25.

Adding to 21420243223 its reverse (32234202412), we get a palindrome (53654445635).

The spelling of 21420243223 in words is "twenty-one billion, four hundred twenty million, two hundred forty-three thousand, two hundred twenty-three".