21437218 has 8 divisors (see below), whose sum is σ = 35079120. Its totient is φ = 9744180.

The previous prime is 21437201. The next prime is 21437231. The reversal of 21437218 is 81273412.

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

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 in 3 ways as a sum of consecutive naturals, for example, 487188 + ... + 487231.

It is an arithmetic number, because the mean of its divisors is an integer number (4384890).

Almost surely, 2^21437218 is an apocalyptic number.

21437218 is a deficient number, since it is larger than the sum of its proper divisors (13641902).

21437218 is a wasteful number, since it uses less digits than its factorization.

21437218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 974432.

The product of its digits is 2688, while the sum is 28.

The square root of 21437218 is about 4630.0343411253. The cubic root of 21437218 is about 277.7939660018.

The spelling of 21437218 in words is "twenty-one million, four hundred thirty-seven thousand, two hundred eighteen".