It is a tau number, because it is divible by the number of its divisors (96).
It is an unprimeable number.
Almost surely, 221397152 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 21397152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34001856).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21397152 is a wasteful number, since it uses less digits than its factorization.
21397152 is an evil number, because the sum of its binary digits is even.
The square root of 21397152 is about 4625.7055678026. The cubic root of 21397152 is about 277.6207931228.
The spelling of 21397152 in words is "twenty-one million, three hundred ninety-seven thousand, one hundred fifty-two".