It is a tau number, because it is divible by the number of its divisors (64).
It is a self number, because there is not a number n which added to its sum of digits gives 21689472.
Almost surely, 221689472 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 21689472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32925600).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21689472 is an equidigital number, since it uses as much as digits as its factorization.
21689472 is an evil number, because the sum of its binary digits is even.
The square root of 21689472 is about 4657.1957227499. The cubic root of 21689472 is about 278.8793301474.
The spelling of 21689472 in words is "twenty-one million, six hundred eighty-nine thousand, four hundred seventy-two".