21230203405 has 4 divisors (see below), whose sum is σ = 25476244092. Its totient is φ = 16984162720.

The previous prime is 21230203403. The next prime is 21230203409. The reversal of 21230203405 is 50430203212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8420264644 + 12809938761 = 91762^2 + 113181^2 .

It is not a de Polignac number, because 21230203405 - 2¹ = 21230203403 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 (21230203403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2123020336 + ... + 2123020345.

It is an arithmetic number, because the mean of its divisors is an integer number (6369061023).

Almost surely, 2^21230203405 is an apocalyptic number.

It is an amenable number.

21230203405 is a deficient number, since it is larger than the sum of its proper divisors (4246040687).

21230203405 is an equidigital number, since it uses as much as digits as its factorization.

21230203405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4246040686.

The product of its (nonzero) digits is 1440, while the sum is 22.

Adding to 21230203405 its reverse (50430203212), we get a palindrome (71660406617).

The spelling of 21230203405 in words is "twenty-one billion, two hundred thirty million, two hundred three thousand, four hundred five".