It is a tau number, because it is divible by the number of its divisors (320).
It is a congruent number.
It is an unprimeable number.
Almost surely, 220891520 is an apocalyptic number.
20891520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 20891520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41469120).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
20891520 is a wasteful number, since it uses less digits than its factorization.
20891520 is an evil number, because the sum of its binary digits is even.
The square root of 20891520 is about 4570.7242314539. The cubic root of 20891520 is about 275.4165368059.
The spelling of 20891520 in words is "twenty million, eight hundred ninety-one thousand, five hundred twenty".