21383808 has 64 divisors (see below), whose sum is σ = 57283200. Its totient is φ = 7067648.

The previous prime is 21383777. The next prime is 21383833. The reversal of 21383808 is 80838312.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89353 + ... + 89591.

It is an arithmetic number, because the mean of its divisors is an integer number (895050).

Almost surely, 2^21383808 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 21383808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28641600).

21383808 is an abundant number, since it is smaller than the sum of its proper divisors (35899392).

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

21383808 is a wasteful number, since it uses less digits than its factorization.

21383808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489 (or 477 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 21383808 is about 4624.2629683010. The cubic root of 21383808 is about 277.5630698297.

The spelling of 21383808 in words is "twenty-one million, three hundred eighty-three thousand, eight hundred eight".