640811066 has 32 divisors (see below), whose sum is σ = 1152271872. Its totient is φ = 261515520.

The previous prime is 640811063. The next prime is 640811071. The reversal of 640811066 is 660118046.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (640811063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11186 + ... + 37506.

It is an arithmetic number, because the mean of its divisors is an integer number (36008496).

Almost surely, 2^640811066 is an apocalyptic number.

640811066 is a deficient number, since it is larger than the sum of its proper divisors (511460806).

640811066 is a wasteful number, since it uses less digits than its factorization.

640811066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26414.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 640811066 is about 25314.2463051934. The cubic root of 640811066 is about 862.1377616577.

The spelling of 640811066 in words is "six hundred forty million, eight hundred eleven thousand, sixty-six".