21286543 has 2 divisors, whose sum is σ = 21286544. Its totient is φ = 21286542.

The previous prime is 21286541. The next prime is 21286579. The reversal of 21286543 is 34568212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21286543 - 2¹ = 21286541 is a prime.

Together with 21286541, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21286541) 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, 10643271 + 10643272.

It is an arithmetic number, because the mean of its divisors is an integer number (10643272).

Almost surely, 2^21286543 is an apocalyptic number.

21286543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21286543 is an equidigital number, since it uses as much as digits as its factorization.

21286543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 31.

The square root of 21286543 is about 4613.7341709292. The cubic root of 21286543 is about 277.1415950350.

The spelling of 21286543 in words is "twenty-one million, two hundred eighty-six thousand, five hundred forty-three".