21784368 has 40 divisors (see below), whose sum is σ = 57056368. Its totient is φ = 7160832.

The previous prime is 21784349. The next prime is 21784369. The reversal of 21784368 is 86348712.

It is not an unprimeable number, because it can be changed into a prime (21784369) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 396 + ... + 6612.

Almost surely, 2^21784368 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21784368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28528184).

21784368 is an abundant number, since it is smaller than the sum of its proper divisors (35272000).

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

21784368 is a wasteful number, since it uses less digits than its factorization.

21784368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6301 (or 6295 counting only the distinct ones).

The product of its digits is 64512, while the sum is 39.

The square root of 21784368 is about 4667.3727084946. The cubic root of 21784368 is about 279.2854569923.

The spelling of 21784368 in words is "twenty-one million, seven hundred eighty-four thousand, three hundred sixty-eight".