640717 has 16 divisors (see below), whose sum is σ = 819072. Its totient is φ = 486720.

The previous prime is 640691. The next prime is 640727. The reversal of 640717 is 717046.

It is a cyclic number.

It is not a de Polignac number, because 640717 - 2⁷ = 640589 is a prime.

It is a Duffinian number.

640717 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 640691 and 640700.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640717.

It is not an unprimeable number, because it can be changed into a prime (640727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4003 + ... + 4159.

It is an arithmetic number, because the mean of its divisors is an integer number (51192).

2⁶⁴⁰⁷¹⁷ is an apocalyptic number.

It is an amenable number.

640717 is a deficient number, since it is larger than the sum of its proper divisors (178355).

640717 is a wasteful number, since it uses less digits than its factorization.

640717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 640717 is about 800.4479995602. The cubic root of 640717 is about 86.2095574590.

The spelling of 640717 in words is "six hundred forty thousand, seven hundred seventeen".