21008808 has 96 divisors (see below), whose sum is σ = 60147360. Its totient is φ = 6868800.

The previous prime is 21008797. The next prime is 21008833. The reversal of 21008808 is 80880012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 196291 + ... + 196397.

It is an arithmetic number, because the mean of its divisors is an integer number (626535).

Almost surely, 2^21008808 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 21008808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30073680).

21008808 is an abundant number, since it is smaller than the sum of its proper divisors (39138552).

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

21008808 is a wasteful number, since it uses less digits than its factorization.

21008808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 27.

The square root of 21008808 is about 4583.5366257945. The cubic root of 21008808 is about 275.9309846341.

The spelling of 21008808 in words is "twenty-one million, eight thousand, eight hundred eight".