640431647848 has 8 divisors (see below), whose sum is σ = 1200809339730. Its totient is φ = 320215823920.

The previous prime is 640431647777. The next prime is 640431647881. The reversal of 640431647848 is 848746134046.

It can be written as a sum of positive squares in only one way, i.e., 469715588164 + 170716059684 = 685358^2 + 413178^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×640431647848² (a number of 24 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (55) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40026977983 + ... + 40026977998.

Almost surely, 2^640431647848 is an apocalyptic number.

It is an amenable number.

640431647848 is a deficient number, since it is larger than the sum of its proper divisors (560377691882).

640431647848 is a wasteful number, since it uses less digits than its factorization.

640431647848 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80053955987 (or 80053955983 counting only the distinct ones).

The product of its (nonzero) digits is 12386304, while the sum is 55.

The spelling of 640431647848 in words is "six hundred forty billion, four hundred thirty-one million, six hundred forty-seven thousand, eight hundred forty-eight".