21909008 has 40 divisors (see below), whose sum is σ = 46577376. Its totient is φ = 9900800.

The previous prime is 21908989. The next prime is 21909029. The reversal of 21909008 is 80090912.

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, 49235 + ... + 49677.

Almost surely, 2^21909008 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 21909008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23288688).

21909008 is an abundant number, since it is smaller than the sum of its proper divisors (24668368).

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

21909008 is a wasteful number, since it uses less digits than its factorization.

21909008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 737 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 21909008 is about 4680.7059296649. The cubic root of 21909008 is about 279.8170914263.

The spelling of 21909008 in words is "twenty-one million, nine hundred nine thousand, eight".