21008208 has 80 divisors (see below), whose sum is σ = 59121216. Its totient is φ = 6389760.

The previous prime is 21008203. The next prime is 21008219. The reversal of 21008208 is 80280012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008203) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 81616 + ... + 81872.

Almost surely, 2^21008208 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 21008208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29560608).

21008208 is an abundant number, since it is smaller than the sum of its proper divisors (38113008).

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

21008208 is a wasteful number, since it uses less digits than its factorization.

21008208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 21008208 is about 4583.4711736849. The cubic root of 21008208 is about 275.9283577967.

The spelling of 21008208 in words is "twenty-one million, eight thousand, two hundred eight".