21123424423 has 2 divisors, whose sum is σ = 21123424424. Its totient is φ = 21123424422.

The previous prime is 21123424417. The next prime is 21123424453. The reversal of 21123424423 is 32442432112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21123424423 - 2²⁹ = 20586553511 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21123424391 and 21123424400.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123424403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561712211 + 10561712212.

It is an arithmetic number, because the mean of its divisors is an integer number (10561712212).

Almost surely, 2^21123424423 is an apocalyptic number.

21123424423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123424423 is an equidigital number, since it uses as much as digits as its factorization.

21123424423 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 28.

Adding to 21123424423 its reverse (32442432112), we get a palindrome (53565856535).

The spelling of 21123424423 in words is "twenty-one billion, one hundred twenty-three million, four hundred twenty-four thousand, four hundred twenty-three".