21859543 has 2 divisors, whose sum is σ = 21859544. Its totient is φ = 21859542.

The previous prime is 21859529. The next prime is 21859547. The reversal of 21859543 is 34595812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21859543 - 2⁹ = 21859031 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21859547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10929771 + 10929772.

It is an arithmetic number, because the mean of its divisors is an integer number (10929772).

Almost surely, 2^21859543 is an apocalyptic number.

21859543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21859543 is an equidigital number, since it uses as much as digits as its factorization.

21859543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43200, while the sum is 37.

The square root of 21859543 is about 4675.4190186549. The cubic root of 21859543 is about 279.6063473323.

The spelling of 21859543 in words is "twenty-one million, eight hundred fifty-nine thousand, five hundred forty-three".