640245 has 8 divisors (see below), whose sum is σ = 1024416. Its totient is φ = 341456.

The previous prime is 640231. The next prime is 640247. The reversal of 640245 is 542046.

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 640245 - 2⁴ = 640229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640247) 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, 21327 + ... + 21356.

It is an arithmetic number, because the mean of its divisors is an integer number (128052).

2⁶⁴⁰²⁴⁵ is an apocalyptic number.

It is an amenable number.

640245 is a deficient number, since it is larger than the sum of its proper divisors (384171).

640245 is a wasteful number, since it uses less digits than its factorization.

640245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42691.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 640245 is about 800.1531103483. The cubic root of 640245 is about 86.1883827921.

The spelling of 640245 in words is "six hundred forty thousand, two hundred forty-five".