640815319891 has 8 divisors (see below), whose sum is σ = 645136365600. Its totient is φ = 636494544768.

The previous prime is 640815319847. The next prime is 640815319901. The reversal of 640815319891 is 198913518046.

It is a happy number.

640815319891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640815319891 - 2³¹ = 638667836243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640815319801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7599835 + ... + 7683691.

It is an arithmetic number, because the mean of its divisors is an integer number (80642045700).

Almost surely, 2^640815319891 is an apocalyptic number.

640815319891 is a deficient number, since it is larger than the sum of its proper divisors (4321045709).

640815319891 is a wasteful number, since it uses less digits than its factorization.

640815319891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135293.

The product of its (nonzero) digits is 1866240, while the sum is 55.

The spelling of 640815319891 in words is "six hundred forty billion, eight hundred fifteen million, three hundred nineteen thousand, eight hundred ninety-one".