640650 has 24 divisors (see below), whose sum is σ = 1589184. Its totient is φ = 170800.

The previous prime is 640649. The next prime is 640663. The reversal of 640650 is 56046.

640650 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1986 + ... + 2285.

It is an arithmetic number, because the mean of its divisors is an integer number (66216).

2⁶⁴⁰⁶⁵⁰ is an apocalyptic number.

640650 is an abundant number, since it is smaller than the sum of its proper divisors (948534).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640650 is a wasteful number, since it uses less digits than its factorization.

640650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4286 (or 4281 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 640650 is about 800.4061469029. The cubic root of 640650 is about 86.2065523664.

Adding to 640650 its reverse (56046), we get a palindrome (696696).

The spelling of 640650 in words is "six hundred forty thousand, six hundred fifty".