640408680 has 320 divisors, whose sum is σ = 2310422400. Its totient is φ = 158630400.

The previous prime is 640408663. The next prime is 640408693. The reversal of 640408680 is 86804046.

640408680 is a `hidden beast` number, since 640 + 4 + 0 + 8 + 6 + 8 + 0 = 666.

640408680 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 79 ways as a sum of consecutive naturals, for example, 6217509 + ... + 6217611.

It is an arithmetic number, because the mean of its divisors is an integer number (7220070).

Almost surely, 2^640408680 is an apocalyptic number.

640408680 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 640408680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1155211200).

640408680 is an abundant number, since it is smaller than the sum of its proper divisors (1670013720).

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

640408680 is a wasteful number, since it uses less digits than its factorization.

640408680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 233 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 640408680 is about 25306.2972400152. The cubic root of 640408680 is about 861.9572691425.

The spelling of 640408680 in words is "six hundred forty million, four hundred eight thousand, six hundred eighty".