21123204134423 has 4 divisors (see below), whose sum is σ = 21211585741920. Its totient is φ = 21034822526928.

The previous prime is 21123204134377. The next prime is 21123204134497. The reversal of 21123204134423 is 32443140232112.

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 21123204134423 - 2³⁰ = 21122130392599 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21123204134423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123204134623) 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 in 3 ways as a sum of consecutive naturals, for example, 44190803390 + ... + 44190803867.

It is an arithmetic number, because the mean of its divisors is an integer number (5302896435480).

Almost surely, 2^{21123204134423} is an apocalyptic number.

21123204134423 is a deficient number, since it is larger than the sum of its proper divisors (88381607497).

21123204134423 is an equidigital number, since it uses as much as digits as its factorization.

21123204134423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88381607496.

The product of its (nonzero) digits is 27648, while the sum is 32.

Adding to 21123204134423 its reverse (32443140232112), we get a palindrome (53566344366535).

The spelling of 21123204134423 in words is "twenty-one trillion, one hundred twenty-three billion, two hundred four million, one hundred thirty-four thousand, four hundred twenty-three".