21218343 has 8 divisors (see below), whose sum is σ = 29266800. Its totient is φ = 13657728.

The previous prime is 21218333. The next prime is 21218359. The reversal of 21218343 is 34381212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21218343 - 2⁵ = 21218311 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21218303) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 121858 + ... + 122031.

It is an arithmetic number, because the mean of its divisors is an integer number (3658350).

Almost surely, 2^21218343 is an apocalyptic number.

21218343 is a deficient number, since it is larger than the sum of its proper divisors (8048457).

21218343 is a wasteful number, since it uses less digits than its factorization.

21218343 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243921.

The product of its digits is 1152, while the sum is 24.

The square root of 21218343 is about 4606.3372651164. The cubic root of 21218343 is about 276.8453001959.

Adding to 21218343 its reverse (34381212), we get a palindrome (55599555).

It can be divided in two parts, 212183 and 43, that added together give a triangular number (212226 = T₆₅₁).

The spelling of 21218343 in words is "twenty-one million, two hundred eighteen thousand, three hundred forty-three".