21543249 has 64 divisors (see below), whose sum is σ = 38191104. Its totient is φ = 10492416.

The previous prime is 21543241. The next prime is 21543271. The reversal of 21543249 is 94234512.

It is not a de Polignac number, because 21543249 - 2³ = 21543241 is a prime.

It is a super-2 number, since 2×21543249² = 928223154952002, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21543241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 295077 + ... + 295149.

It is an arithmetic number, because the mean of its divisors is an integer number (596736).

Almost surely, 2^21543249 is an apocalyptic number.

It is an amenable number.

21543249 is a deficient number, since it is larger than the sum of its proper divisors (16647855).

21543249 is a wasteful number, since it uses less digits than its factorization.

21543249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166.

The product of its digits is 8640, while the sum is 30.

The square root of 21543249 is about 4641.4705643794. The cubic root of 21543249 is about 278.2512134978.

The spelling of 21543249 in words is "twenty-one million, five hundred forty-three thousand, two hundred forty-nine".