21065543 has 8 divisors (see below), whose sum is σ = 21751200. Its totient is φ = 20386080.

The previous prime is 21065501. The next prime is 21065549. The reversal of 21065543 is 34556012.

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 21065543 - 2⁶ = 21065479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5933 + ... + 8793.

It is an arithmetic number, because the mean of its divisors is an integer number (2718900).

Almost surely, 2^21065543 is an apocalyptic number.

21065543 is a deficient number, since it is larger than the sum of its proper divisors (685657).

21065543 is a wasteful number, since it uses less digits than its factorization.

21065543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3097.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21065543 is about 4589.7214512430. The cubic root of 21065543 is about 276.1791483770.

The spelling of 21065543 in words is "twenty-one million, sixty-five thousand, five hundred forty-three".