21105142505543 has 16 divisors (see below), whose sum is σ = 21264262411392. Its totient is φ = 20946661344000.

The previous prime is 21105142505471. The next prime is 21105142505567. The reversal of 21105142505543 is 34550524150112.

It is a cyclic number.

It is not a de Polignac number, because 21105142505543 - 2¹⁶ = 21105142440007 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21105142505497 and 21105142505506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105142505243) 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, 290936705 + ... + 291009237.

It is an arithmetic number, because the mean of its divisors is an integer number (1329016400712).

Almost surely, 2^{21105142505543} is an apocalyptic number.

21105142505543 is a deficient number, since it is larger than the sum of its proper divisors (159119905849).

21105142505543 is a wasteful number, since it uses less digits than its factorization.

21105142505543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76906.

The product of its (nonzero) digits is 120000, while the sum is 38.

Adding to 21105142505543 its reverse (34550524150112), we get a palindrome (55655666655655).

The spelling of 21105142505543 in words is "twenty-one trillion, one hundred five billion, one hundred forty-two million, five hundred five thousand, five hundred forty-three".