21878304 has 72 divisors (see below), whose sum is σ = 66821328. Its totient is φ = 6249600.

The previous prime is 21878293. The next prime is 21878309. The reversal of 21878304 is 40387812.

It is not an unprimeable number, because it can be changed into a prime (21878309) 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 11 ways as a sum of consecutive naturals, for example, 2379 + ... + 7029.

It is an arithmetic number, because the mean of its divisors is an integer number (928074).

Almost surely, 2^21878304 is an apocalyptic number.

21878304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21878304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33410664).

21878304 is an abundant number, since it is smaller than the sum of its proper divisors (44943024).

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

21878304 is a wasteful number, since it uses less digits than its factorization.

21878304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4678 (or 4663 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 21878304 is about 4677.4249325884. The cubic root of 21878304 is about 279.6863153763.

The spelling of 21878304 in words is "twenty-one million, eight hundred seventy-eight thousand, three hundred four".