21273218 has 8 divisors (see below), whose sum is σ = 32652048. Its totient is φ = 10389204.

The previous prime is 21273191. The next prime is 21273253. The reversal of 21273218 is 81237212.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123596 + ... + 123767.

It is an arithmetic number, because the mean of its divisors is an integer number (4081506).

Almost surely, 2^21273218 is an apocalyptic number.

21273218 is a deficient number, since it is larger than the sum of its proper divisors (11378830).

21273218 is a wasteful number, since it uses less digits than its factorization.

21273218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247408.

The product of its digits is 1344, while the sum is 26.

The square root of 21273218 is about 4612.2898868133. The cubic root of 21273218 is about 277.0837543828.

It can be divided in two parts, 21 and 273218, that multiplied together give a triangular number (5737578 = T₃₃₈₇).

The spelling of 21273218 in words is "twenty-one million, two hundred seventy-three thousand, two hundred eighteen".