640256136640 has 56 divisors (see below), whose sum is σ = 1549603577952. Its totient is φ = 251904046080.

The previous prime is 640256136629. The next prime is 640256136697. The reversal of 640256136640 is 46631652046.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16380484 + ... + 16419523.

Almost surely, 2^640256136640 is an apocalyptic number.

It is an amenable number.

640256136640 is an abundant number, since it is smaller than the sum of its proper divisors (909347441312).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640256136640 is a wasteful number, since it uses less digits than its factorization.

640256136640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32800085 (or 32800075 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 43.

Adding to 640256136640 its reverse (46631652046), we get a palindrome (686887788686).

The spelling of 640256136640 in words is "six hundred forty billion, two hundred fifty-six million, one hundred thirty-six thousand, six hundred forty".