640930806 has 40 divisors (see below), whose sum is σ = 1460523240. Its totient is φ = 210019392.

The previous prime is 640930783. The next prime is 640930813. The reversal of 640930806 is 608039046.

640930806 is a `hidden beast` number, since 640 + 9 + 3 + 0 + 8 + 0 + 6 = 666.

It is a Curzon number.

It is a congruent number.

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, 23971 + ... + 43086.

It is an arithmetic number, because the mean of its divisors is an integer number (36513081).

Almost surely, 2^640930806 is an apocalyptic number.

640930806 is an abundant number, since it is smaller than the sum of its proper divisors (819592434).

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

640930806 is a wasteful number, since it uses less digits than its factorization.

640930806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67130 (or 67121 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640930806 is about 25316.6112661233. The cubic root of 640930806 is about 862.1914571237.

The spelling of 640930806 in words is "six hundred forty million, nine hundred thirty thousand, eight hundred six".