21105543 has 8 divisors (see below), whose sum is σ = 28230768. Its totient is φ = 14025344.

The previous prime is 21105509. The next prime is 21105547. The reversal of 21105543 is 34550112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21105543 - 2⁶ = 21105479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105547) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10146 + ... + 12047.

It is an arithmetic number, because the mean of its divisors is an integer number (3528846).

Almost surely, 2^21105543 is an apocalyptic number.

21105543 is a deficient number, since it is larger than the sum of its proper divisors (7125225).

21105543 is a wasteful number, since it uses less digits than its factorization.

21105543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22513.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21105543 is about 4594.0769475489. The cubic root of 21105543 is about 276.3538441041.

Adding to 21105543 its reverse (34550112), we get a palindrome (55655655).

The spelling of 21105543 in words is "twenty-one million, one hundred five thousand, five hundred forty-three".