21843218 has 4 divisors (see below), whose sum is σ = 32764830. Its totient is φ = 10921608.

The previous prime is 21843167. The next prime is 21843223. The reversal of 21843218 is 81234812.

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

It can be written as a sum of positive squares in only one way, i.e., 20313049 + 1530169 = 4507^2 + 1237^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5460803 + ... + 5460806.

Almost surely, 2^21843218 is an apocalyptic number.

21843218 is a deficient number, since it is larger than the sum of its proper divisors (10921612).

21843218 is a wasteful number, since it uses less digits than its factorization.

21843218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10921611.

The product of its digits is 3072, while the sum is 29.

The square root of 21843218 is about 4673.6728597539. The cubic root of 21843218 is about 279.5367254074.

The spelling of 21843218 in words is "twenty-one million, eight hundred forty-three thousand, two hundred eighteen".