21689008 has 60 divisors (see below), whose sum is σ = 48981240. Its totient is φ = 9264640.

The previous prime is 21688987. The next prime is 21689021. The reversal of 21689008 is 80098612.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32583 + ... + 33241.

It is an arithmetic number, because the mean of its divisors is an integer number (816354).

Almost surely, 2^21689008 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 21689008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24490620).

21689008 is an abundant number, since it is smaller than the sum of its proper divisors (27292232).

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

21689008 is a wasteful number, since it uses less digits than its factorization.

21689008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706 (or 689 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 21689008 is about 4657.1459070980. The cubic root of 21689008 is about 278.8773414571.

The spelling of 21689008 in words is "twenty-one million, six hundred eighty-nine thousand, eight".