640506 has 8 divisors (see below), whose sum is σ = 1281024. Its totient is φ = 213500.

The previous prime is 640499. The next prime is 640529. The reversal of 640506 is 605046.

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

640506 is an admirable number.

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640506.

It is an unprimeable number.

640506 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53370 + ... + 53381.

It is an arithmetic number, because the mean of its divisors is an integer number (160128).

2⁶⁴⁰⁵⁰⁶ is an apocalyptic number.

640506 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

640506 is a wasteful number, since it uses less digits than its factorization.

640506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106756.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 640506 is about 800.3161875159. The cubic root of 640506 is about 86.2000929509.

The spelling of 640506 in words is "six hundred forty thousand, five hundred six".