21308543 has 2 divisors, whose sum is σ = 21308544. Its totient is φ = 21308542.

The previous prime is 21308527. The next prime is 21308579. The reversal of 21308543 is 34580312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21308543 - 2⁴ = 21308527 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21338543) 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 as a sum of consecutive naturals, namely, 10654271 + 10654272.

It is an arithmetic number, because the mean of its divisors is an integer number (10654272).

Almost surely, 2^21308543 is an apocalyptic number.

21308543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21308543 is an equidigital number, since it uses as much as digits as its factorization.

21308543 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21308543 is about 4616.1177411327. The cubic root of 21308543 is about 277.2370389939.

Adding to 21308543 its reverse (34580312), we get a palindrome (55888855).

The spelling of 21308543 in words is "twenty-one million, three hundred eight thousand, five hundred forty-three".