640815319847 has 2 divisors, whose sum is σ = 640815319848. Its totient is φ = 640815319846.

The previous prime is 640815319811. The next prime is 640815319901. The reversal of 640815319847 is 748913518046.

It is a happy number.

640815319847 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640815319847 - 2²² = 640811125543 is a prime.

It is a super-2 number, since 2×640815319847² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640815319792 and 640815319801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640815319247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320407659923 + 320407659924.

It is an arithmetic number, because the mean of its divisors is an integer number (320407659924).

Almost surely, 2^640815319847 is an apocalyptic number.

640815319847 is a deficient number, since it is larger than the sum of its proper divisors (1).

640815319847 is an equidigital number, since it uses as much as digits as its factorization.

640815319847 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5806080, while the sum is 56.

The spelling of 640815319847 in words is "six hundred forty billion, eight hundred fifteen million, three hundred nineteen thousand, eight hundred forty-seven".