640839702517 has 4 divisors (see below), whose sum is σ = 732388231456. Its totient is φ = 549291173580.

The previous prime is 640839702511. The next prime is 640839702521. The reversal of 640839702517 is 715207938046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 640839702517 - 2³ = 640839702509 is a prime.

It is a super-2 number, since 2×640839702517² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640839702511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45774264459 + ... + 45774264472.

It is an arithmetic number, because the mean of its divisors is an integer number (183097057864).

It is a 2-persistent number, because it is pandigital, and so is 2⋅640839702517 = 1281679405034, but 3⋅640839702517 = 1922519107551 is not.

Almost surely, 2^640839702517 is an apocalyptic number.

It is an amenable number.

640839702517 is a deficient number, since it is larger than the sum of its proper divisors (91548528939).

640839702517 is an equidigital number, since it uses as much as digits as its factorization.

640839702517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91548528938.

The product of its (nonzero) digits is 2540160, while the sum is 52.

The spelling of 640839702517 in words is "six hundred forty billion, eight hundred thirty-nine million, seven hundred two thousand, five hundred seventeen".