21224218 has 8 divisors (see below), whose sum is σ = 32358420. Its totient is φ = 10438080.

The previous prime is 21224207. The next prime is 21224249. The reversal of 21224218 is 81242212.

It can be written as a sum of positive squares in 2 ways, for example, as 21132409 + 91809 = 4597^2 + 303^2 .

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86863 + ... + 87106.

Almost surely, 2^21224218 is an apocalyptic number.

21224218 is a deficient number, since it is larger than the sum of its proper divisors (11134202).

21224218 is a wasteful number, since it uses less digits than its factorization.

21224218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174032.

The product of its digits is 512, while the sum is 22.

The square root of 21224218 is about 4606.9749293870. The cubic root of 21224218 is about 276.8708490971.

The spelling of 21224218 in words is "twenty-one million, two hundred twenty-four thousand, two hundred eighteen".