821197440 is a `hidden beast` number, since 8 + 21 + 197 + 440 = 666.
It is a tau number, because it is divible by the number of its divisors (640).
It is an unprimeable number.
Almost surely, 2821197440 is an apocalyptic number.
821197440 is a gapful number since it is divisible by the number (80) 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 821197440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1753551360).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
821197440 is a wasteful number, since it uses less digits than its factorization.
821197440 is an odious number, because the sum of its binary digits is odd.
The square root of 821197440 is about 28656.5427084287. The cubic root of 821197440 is about 936.4455472493.
The spelling of 821197440 in words is "eight hundred twenty-one million, one hundred ninety-seven thousand, four hundred forty".