640206606 has 64 divisors (see below), whose sum is σ = 1430102016. Its totient is φ = 189734400.

The previous prime is 640206571. The next prime is 640206607. The reversal of 640206606 is 606602046.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640206607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 654790 + ... + 655766.

It is an arithmetic number, because the mean of its divisors is an integer number (22345344).

Almost surely, 2^640206606 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640206606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (715051008).

640206606 is an abundant number, since it is smaller than the sum of its proper divisors (789895410).

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

640206606 is a wasteful number, since it uses less digits than its factorization.

640206606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297.

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 640206606 is about 25302.3043614608. The cubic root of 640206606 is about 861.8665991886.

The spelling of 640206606 in words is "six hundred forty million, two hundred six thousand, six hundred six".