640172357817 has 16 divisors (see below), whose sum is σ = 857476863360. Its totient is φ = 424825782912.

The previous prime is 640172357777. The next prime is 640172357843. The reversal of 640172357817 is 718753271046.

It is not a de Polignac number, because 640172357817 - 2⁷ = 640172357689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640172357817.

It is not an unprimeable number, because it can be changed into a prime (640172352817) 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, 2292828 + ... + 2556834.

It is an arithmetic number, because the mean of its divisors is an integer number (53592303960).

Almost surely, 2^640172357817 is an apocalyptic number.

It is an amenable number.

640172357817 is a deficient number, since it is larger than the sum of its proper divisors (217304505543).

640172357817 is a wasteful number, since it uses less digits than its factorization.

640172357817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267712.

The product of its (nonzero) digits is 1975680, while the sum is 51.

The spelling of 640172357817 in words is "six hundred forty billion, one hundred seventy-two million, three hundred fifty-seven thousand, eight hundred seventeen".