640805814 has 96 divisors (see below), whose sum is σ = 1558103040. Its totient is φ = 188697600.

The previous prime is 640805807. The next prime is 640805819. The reversal of 640805814 is 418508046.

640805814 is a `hidden beast` number, since 640 + 8 + 0 + 5 + 8 + 1 + 4 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640805819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1110294 + ... + 1110870.

It is an arithmetic number, because the mean of its divisors is an integer number (16230240).

Almost surely, 2^640805814 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640805814, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (779051520).

640805814 is an abundant number, since it is smaller than the sum of its proper divisors (917297226).

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

640805814 is a wasteful number, since it uses less digits than its factorization.

640805814 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 746 (or 743 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The square root of 640805814 is about 25314.1425689277. The cubic root of 640805814 is about 862.1354063301.

The spelling of 640805814 in words is "six hundred forty million, eight hundred five thousand, eight hundred fourteen".