640706 has 8 divisors (see below), whose sum is σ = 1048464. Its totient is φ = 291220.

The previous prime is 640691. The next prime is 640727. The reversal of 640706 is 607046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640706.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14540 + ... + 14583.

It is an arithmetic number, because the mean of its divisors is an integer number (131058).

2⁶⁴⁰⁷⁰⁶ is an apocalyptic number.

640706 is a deficient number, since it is larger than the sum of its proper divisors (407758).

640706 is a wasteful number, since it uses less digits than its factorization.

640706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29136.

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 640706 is about 800.4411283786. The cubic root of 640706 is about 86.2090641000.

The spelling of 640706 in words is "six hundred forty thousand, seven hundred six".