640543680 has 672 divisors, whose sum is σ = 2814523200. Its totient is φ = 136249344.

The previous prime is 640543649. The next prime is 640543681. The reversal of 640543680 is 86345046.

640543680 is a `hidden beast` number, since 640 + 5 + 4 + 3 + 6 + 8 + 0 = 666.

640543680 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (672).

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 (640543681) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7197076 + ... + 7197164.

Almost surely, 2^640543680 is an apocalyptic number.

640543680 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 640543680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1407261600).

640543680 is an abundant number, since it is smaller than the sum of its proper divisors (2173979520).

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

640543680 is a wasteful number, since it uses less digits than its factorization.

640543680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 640543680 is about 25308.9644197466. The cubic root of 640543680 is about 862.0178325813.

The spelling of 640543680 in words is "six hundred forty million, five hundred forty-three thousand, six hundred eighty".