640831437839 has 4 divisors (see below), whose sum is σ = 641521246560. Its totient is φ = 640141629120.

The previous prime is 640831437811. The next prime is 640831437853. The reversal of 640831437839 is 938734138046.

640831437839 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 938734138046 = 2 ⋅469367069023.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640831437839 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 (640831430839) 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, 344902967 + ... + 344904824.

It is an arithmetic number, because the mean of its divisors is an integer number (160380311640).

Almost surely, 2^640831437839 is an apocalyptic number.

640831437839 is a deficient number, since it is larger than the sum of its proper divisors (689808721).

640831437839 is an equidigital number, since it uses as much as digits as its factorization.

640831437839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 689808720.

The product of its (nonzero) digits is 10450944, while the sum is 56.

The spelling of 640831437839 in words is "six hundred forty billion, eight hundred thirty-one million, four hundred thirty-seven thousand, eight hundred thirty-nine".