21843859 has 4 divisors (see below), whose sum is σ = 22793616. Its totient is φ = 20894104.

The previous prime is 21843853. The next prime is 21843889. The reversal of 21843859 is 95834812.

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

It is a cyclic number.

It is not a de Polignac number, because 21843859 - 2³ = 21843851 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21843851) 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, 474844 + ... + 474889.

It is an arithmetic number, because the mean of its divisors is an integer number (5698404).

Almost surely, 2^21843859 is an apocalyptic number.

21843859 is a deficient number, since it is larger than the sum of its proper divisors (949757).

21843859 is an equidigital number, since it uses as much as digits as its factorization.

21843859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 949756.

The product of its digits is 69120, while the sum is 40.

The square root of 21843859 is about 4673.7414348678. The cubic root of 21843859 is about 279.5394597616.

The spelling of 21843859 in words is "twenty-one million, eight hundred forty-three thousand, eight hundred fifty-nine".