640631425066 has 4 divisors (see below), whose sum is σ = 960947137602. Its totient is φ = 320315712532.

The previous prime is 640631425013. The next prime is 640631425067. The reversal of 640631425066 is 660524136046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 623712960025 + 16918465041 = 789755^2 + 130071^2 .

It is not an unprimeable number, because it can be changed into a prime (640631425067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160157856265 + ... + 160157856268.

Almost surely, 2^640631425066 is an apocalyptic number.

640631425066 is a deficient number, since it is larger than the sum of its proper divisors (320315712536).

640631425066 is a wasteful number, since it uses less digits than its factorization.

640631425066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320315712535.

The product of its (nonzero) digits is 622080, while the sum is 43.

The spelling of 640631425066 in words is "six hundred forty billion, six hundred thirty-one million, four hundred twenty-five thousand, sixty-six".