640785 has 8 divisors (see below), whose sum is σ = 1025280. Its totient is φ = 341744.

The previous prime is 640777. The next prime is 640793. The reversal of 640785 is 587046.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (640777) and next prime (640793).

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 640785 - 2³ = 640777 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21345 + ... + 21374.

It is an arithmetic number, because the mean of its divisors is an integer number (128160).

2⁶⁴⁰⁷⁸⁵ is an apocalyptic number.

It is an amenable number.

640785 is a deficient number, since it is larger than the sum of its proper divisors (384495).

640785 is a wasteful number, since it uses less digits than its factorization.

640785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42727.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 640785 is about 800.4904746466. The cubic root of 640785 is about 86.2126071895.

The spelling of 640785 in words is "six hundred forty thousand, seven hundred eighty-five".