640886 has 8 divisors (see below), whose sum is σ = 968760. Its totient is φ = 317968.

The previous prime is 640873. The next prime is 640891. The reversal of 640886 is 688046.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

640886 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 896 + ... + 1443.

It is an arithmetic number, because the mean of its divisors is an integer number (121095).

2⁶⁴⁰⁸⁸⁶ is an apocalyptic number.

640886 is a deficient number, since it is larger than the sum of its proper divisors (327874).

640886 is a wasteful number, since it uses less digits than its factorization.

640886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2478.

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 640886 is about 800.5535584831. The cubic root of 640886 is about 86.2171365381.

The spelling of 640886 in words is "six hundred forty thousand, eight hundred eighty-six".