640959 has 8 divisors (see below), whose sum is σ = 932352. Its totient is φ = 388440.

The previous prime is 640957. The next prime is 640963. The reversal of 640959 is 959046.

It is a happy number.

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

It is not a de Polignac number, because 640959 - 2¹ = 640957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 19423 = 640959 / (6 + 4 + 0 + 9 + 5 + 9).

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 640959.

It is not an unprimeable number, because it can be changed into a prime (640957) 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, 9679 + ... + 9744.

It is an arithmetic number, because the mean of its divisors is an integer number (116544).

2⁶⁴⁰⁹⁵⁹ is an apocalyptic number.

640959 is a deficient number, since it is larger than the sum of its proper divisors (291393).

640959 is a wasteful number, since it uses less digits than its factorization.

640959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19437.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 640959 is about 800.5991506366. The cubic root of 640959 is about 86.2204099294.

The spelling of 640959 in words is "six hundred forty thousand, nine hundred fifty-nine".