640305 has 48 divisors (see below), whose sum is σ = 1257984. Its totient is φ = 311040.

The previous prime is 640303. The next prime is 640307. The reversal of 640305 is 503046.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (640303) and next prime (640307).

It is not a de Polignac number, because 640305 - 2¹ = 640303 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640305.

It is not an unprimeable number, because it can be changed into a prime (640303) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20640 + ... + 20670.

It is an arithmetic number, because the mean of its divisors is an integer number (26208).

2⁶⁴⁰³⁰⁵ is an apocalyptic number.

It is an amenable number.

640305 is a deficient number, since it is larger than the sum of its proper divisors (617679).

640305 is a wasteful number, since it uses less digits than its factorization.

640305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 56 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 640305 is about 800.1906022942. The cubic root of 640305 is about 86.1910750643.

The spelling of 640305 in words is "six hundred forty thousand, three hundred five".