640865718771305 has 16 divisors (see below), whose sum is σ = 769860301077504. Its totient is φ = 512144955241920.

The previous prime is 640865718771293. The next prime is 640865718771361. The reversal of 640865718771305 is 503177817568046.

It is not a de Polignac number, because 640865718771305 - 2²² = 640865714577001 is a prime.

It is a super-2 number, since 2×640865718771305² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1622382932 + ... + 1622777898.

It is an arithmetic number, because the mean of its divisors is an integer number (48116268817344).

Almost surely, 2^{640865718771305} is an apocalyptic number.

It is an amenable number.

640865718771305 is a deficient number, since it is larger than the sum of its proper divisors (128994582306199).

640865718771305 is a wasteful number, since it uses less digits than its factorization.

640865718771305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740776.

The product of its (nonzero) digits is 237081600, while the sum is 68.

The spelling of 640865718771305 in words is "six hundred forty trillion, eight hundred sixty-five billion, seven hundred eighteen million, seven hundred seventy-one thousand, three hundred five".