21405704042423 has 16 divisors (see below), whose sum is σ = 22764151781280. Its totient is φ = 20058303691776.

The previous prime is 21405704042417. The next prime is 21405704042449. The reversal of 21405704042423 is 32424040750412.

It is a cyclic number.

It is not a de Polignac number, because 21405704042423 - 2⁸ = 21405704042167 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405704042453) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45631061 + ... + 46097777.

It is an arithmetic number, because the mean of its divisors is an integer number (1422759486330).

Almost surely, 2^{21405704042423} is an apocalyptic number.

21405704042423 is a deficient number, since it is larger than the sum of its proper divisors (1358447738857).

21405704042423 is a wasteful number, since it uses less digits than its factorization.

21405704042423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478546.

The product of its (nonzero) digits is 215040, while the sum is 38.

Adding to 21405704042423 its reverse (32424040750412), we get a palindrome (53829744792835).

The spelling of 21405704042423 in words is "twenty-one trillion, four hundred five billion, seven hundred four million, forty-two thousand, four hundred twenty-three".