21218449 has 8 divisors (see below), whose sum is σ = 24385088. Its totient is φ = 18085680.

The previous prime is 21218441. The next prime is 21218467. The reversal of 21218449 is 94481212.

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

It is a cyclic number.

It is not a de Polignac number, because 21218449 - 2³ = 21218441 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21218449.

It is not an unprimeable number, because it can be changed into a prime (21218441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7107 + ... + 9640.

It is an arithmetic number, because the mean of its divisors is an integer number (3048136).

Almost surely, 2^21218449 is an apocalyptic number.

It is an amenable number.

21218449 is a deficient number, since it is larger than the sum of its proper divisors (3166639).

21218449 is a wasteful number, since it uses less digits than its factorization.

21218449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16935.

The product of its digits is 4608, while the sum is 31.

The square root of 21218449 is about 4606.3487709899. The cubic root of 21218449 is about 276.8457612050.

The spelling of 21218449 in words is "twenty-one million, two hundred eighteen thousand, four hundred forty-nine".