640828800 has 192 divisors, whose sum is σ = 2345571600. Its totient is φ = 170864640.

The previous prime is 640828757. The next prime is 640828801. The reversal of 640828800 is 8828046.

640828800 is a `hidden beast` number, since 640 + 8 + 2 + 8 + 8 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640828801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 82692 + ... + 90108.

Almost surely, 2^640828800 is an apocalyptic number.

640828800 is a gapful number since it is divisible by the number (60) 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 640828800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1172785800).

640828800 is an abundant number, since it is smaller than the sum of its proper divisors (1704742800).

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

640828800 is a wasteful number, since it uses less digits than its factorization.

640828800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7450 (or 7427 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 640828800 is about 25314.5965798391. The cubic root of 640828800 is about 862.1457146051.

The spelling of 640828800 in words is "six hundred forty million, eight hundred twenty-eight thousand, eight hundred".