640327680 has 280 divisors, whose sum is σ = 2307447252. Its totient is φ = 169869312.

The previous prime is 640327657. The next prime is 640327711. The reversal of 640327680 is 86723046.

640327680 is a `hidden beast` number, since 640 + 3 + 2 + 7 + 6 + 8 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 613453824 + 26873856 = 24768^2 + 5184^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3317664 + ... + 3317856.

Almost surely, 2^640327680 is an apocalyptic number.

640327680 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 640327680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1153723626).

640327680 is an abundant number, since it is smaller than the sum of its proper divisors (1667119572).

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

640327680 is an equidigital number, since it uses as much as digits as its factorization.

640327680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 236 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 640327680 is about 25304.6967972351. The cubic root of 640327680 is about 861.9209269937.

The spelling of 640327680 in words is "six hundred forty million, three hundred twenty-seven thousand, six hundred eighty".