21923218 has 8 divisors (see below), whose sum is σ = 32966460. Its totient is φ = 10934400.

The previous prime is 21923179. The next prime is 21923227. The reversal of 21923218 is 81232912.

It can be written as a sum of positive squares in 2 ways, for example, as 21409129 + 514089 = 4627^2 + 717^2 .

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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12583 + ... + 14218.

Almost surely, 2^21923218 is an apocalyptic number.

21923218 is a deficient number, since it is larger than the sum of its proper divisors (11043242).

21923218 is a wasteful number, since it uses less digits than its factorization.

21923218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27212.

The product of its digits is 1728, while the sum is 28.

The square root of 21923218 is about 4682.2236170435. The cubic root of 21923218 is about 279.8775740298.

The spelling of 21923218 in words is "twenty-one million, nine hundred twenty-three thousand, two hundred eighteen".