21543043 has 4 divisors (see below), whose sum is σ = 22044088. Its totient is φ = 21042000.

The previous prime is 21543031. The next prime is 21543077. The reversal of 21543043 is 34034512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21543043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21543013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250458 + ... + 250543.

It is an arithmetic number, because the mean of its divisors is an integer number (5511022).

Almost surely, 2^21543043 is an apocalyptic number.

21543043 is a deficient number, since it is larger than the sum of its proper divisors (501045).

21543043 is an equidigital number, since it uses as much as digits as its factorization.

21543043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501044.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 21543043 is about 4641.4483730836. The cubic root of 21543043 is about 278.2503266007.

Adding to 21543043 its reverse (34034512), we get a palindrome (55577555).

The spelling of 21543043 in words is "twenty-one million, five hundred forty-three thousand, forty-three".