21203404423 has 2 divisors, whose sum is σ = 21203404424. Its totient is φ = 21203404422.

The previous prime is 21203404421. The next prime is 21203404451. The reversal of 21203404423 is 32440430212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21203404423 - 2¹ = 21203404421 is a prime.

Together with 21203404421, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21203404421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601702211 + 10601702212.

It is an arithmetic number, because the mean of its divisors is an integer number (10601702212).

Almost surely, 2^21203404423 is an apocalyptic number.

21203404423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203404423 is an equidigital number, since it uses as much as digits as its factorization.

21203404423 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21203404423 its reverse (32440430212), we get a palindrome (53643834635).

The spelling of 21203404423 in words is "twenty-one billion, two hundred three million, four hundred four thousand, four hundred twenty-three".