640815319769 has 2 divisors, whose sum is σ = 640815319770. Its totient is φ = 640815319768.

The previous prime is 640815319759. The next prime is 640815319801. The reversal of 640815319769 is 967913518046.

640815319769 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 can be written as a sum of positive squares in only one way, i.e., 592764487744 + 48050832025 = 769912^2 + 219205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640815319769 is a prime.

It is a super-2 number, since 2×640815319769² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (640815319759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320407659884 + 320407659885.

It is an arithmetic number, because the mean of its divisors is an integer number (320407659885).

Almost surely, 2^640815319769 is an apocalyptic number.

It is an amenable number.

640815319769 is a deficient number, since it is larger than the sum of its proper divisors (1).

640815319769 is an equidigital number, since it uses as much as digits as its factorization.

640815319769 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9797760, while the sum is 59.

The spelling of 640815319769 in words is "six hundred forty billion, eight hundred fifteen million, three hundred nineteen thousand, seven hundred sixty-nine".