21648438 has 32 divisors (see below), whose sum is σ = 54981120. Its totient is φ = 6185160.

The previous prime is 21648421. The next prime is 21648469. The reversal of 21648438 is 83484612.

21648438 is a `hidden beast` number, since 2 + 1 + 648 + 4 + 3 + 8 = 666.

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 15 ways as a sum of consecutive naturals, for example, 28258 + ... + 29013.

It is an arithmetic number, because the mean of its divisors is an integer number (1718160).

Almost surely, 2^21648438 is an apocalyptic number.

21648438 is an abundant number, since it is smaller than the sum of its proper divisors (33332682).

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

21648438 is a wasteful number, since it uses less digits than its factorization.

21648438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57289 (or 57283 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 21648438 is about 4652.7881963399. The cubic root of 21648438 is about 278.7033498585.

The spelling of 21648438 in words is "twenty-one million, six hundred forty-eight thousand, four hundred thirty-eight".