21243318 has 8 divisors (see below), whose sum is σ = 42486648. Its totient is φ = 7081104.

The previous prime is 21243307. The next prime is 21243331. The reversal of 21243318 is 81334212.

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

21243318 is an admirable number.

It is a congruent number.

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, 1770271 + ... + 1770282.

It is an arithmetic number, because the mean of its divisors is an integer number (5310831).

Almost surely, 2^21243318 is an apocalyptic number.

21243318 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21243318 is a wasteful number, since it uses less digits than its factorization.

21243318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3540558.

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

The square root of 21243318 is about 4609.0474070029. The cubic root of 21243318 is about 276.9538776401.

The spelling of 21243318 in words is "twenty-one million, two hundred forty-three thousand, three hundred eighteen".