640139556109 has 4 divisors (see below), whose sum is σ = 640143195616. Its totient is φ = 640135916604.

The previous prime is 640139556097. The next prime is 640139556151. The reversal of 640139556109 is 901655931046.

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 a de Polignac number, because none of the positive numbers 2^k-640139556109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640139556409) 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, 1541769 + ... + 1912414.

It is an arithmetic number, because the mean of its divisors is an integer number (160035798904).

Almost surely, 2^640139556109 is an apocalyptic number.

It is an amenable number.

640139556109 is a deficient number, since it is larger than the sum of its proper divisors (3639507).

640139556109 is a wasteful number, since it uses less digits than its factorization.

640139556109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3639506.

The product of its (nonzero) digits is 874800, while the sum is 49.

The spelling of 640139556109 in words is "six hundred forty billion, one hundred thirty-nine million, five hundred fifty-six thousand, one hundred nine".