640757 has 8 divisors (see below), whose sum is σ = 720384. Its totient is φ = 565488.

The previous prime is 640741. The next prime is 640771. The reversal of 640757 is 757046.

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

It is a cyclic number.

It is not a de Polignac number, because 640757 - 2⁴ = 640741 is a prime.

It is a Duffinian number.

It is a congruent number.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 773 + ... + 1370.

It is an arithmetic number, because the mean of its divisors is an integer number (90048).

2⁶⁴⁰⁷⁵⁷ is an apocalyptic number.

It is an amenable number.

640757 is a deficient number, since it is larger than the sum of its proper divisors (79627).

640757 is a wasteful number, since it uses less digits than its factorization.

640757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2179.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 640757 is about 800.4729851781. The cubic root of 640757 is about 86.2113514443.

The spelling of 640757 in words is "six hundred forty thousand, seven hundred fifty-seven".