640711 has 8 divisors (see below), whose sum is σ = 678240. Its totient is φ = 604032.

The previous prime is 640691. The next prime is 640727. The reversal of 640711 is 117046.

It is a happy number.

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 640711 - 2⁷ = 640583 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 (640741) 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 7 ways as a sum of consecutive naturals, for example, 1891 + ... + 2203.

It is an arithmetic number, because the mean of its divisors is an integer number (84780).

2⁶⁴⁰⁷¹¹ is an apocalyptic number.

640711 is a deficient number, since it is larger than the sum of its proper divisors (37529).

640711 is a wasteful number, since it uses less digits than its factorization.

640711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 640711 is about 800.4442516503. Note that the first 3 decimals coincide. The cubic root of 640711 is about 86.2092883548.

Adding to 640711 its reverse (117046), we get a palindrome (757757).

The spelling of 640711 in words is "six hundred forty thousand, seven hundred eleven".