21543541 has 8 divisors (see below), whose sum is σ = 21963200. Its totient is φ = 21127392.

The previous prime is 21543527. The next prime is 21543551. The reversal of 21543541 is 14534512.

It is a happy number.

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 21543541 - 2¹¹ = 21541493 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 (21543551) 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, 13786 + ... + 15268.

It is an arithmetic number, because the mean of its divisors is an integer number (2745400).

Almost surely, 2^21543541 is an apocalyptic number.

It is an amenable number.

21543541 is a deficient number, since it is larger than the sum of its proper divisors (419659).

21543541 is a wasteful number, since it uses less digits than its factorization.

21543541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1755.

The product of its digits is 2400, while the sum is 25.

The square root of 21543541 is about 4641.5020198207. The cubic root of 21543541 is about 278.2524706432.

The spelling of 21543541 in words is "twenty-one million, five hundred forty-three thousand, five hundred forty-one".