640680440329 has 2 divisors, whose sum is σ = 640680440330. Its totient is φ = 640680440328.

The previous prime is 640680440299. The next prime is 640680440353. The reversal of 640680440329 is 923044086046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 402977388025 + 237703052304 = 634805^2 + 487548^2 .

It is a cyclic number.

It is not a de Polignac number, because 640680440329 - 2³¹ = 638532956681 is a prime.

It is a super-3 number, since 3×640680440329³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (640680440129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320340220164 + 320340220165.

It is an arithmetic number, because the mean of its divisors is an integer number (320340220165).

Almost surely, 2^640680440329 is an apocalyptic number.

It is an amenable number.

640680440329 is a deficient number, since it is larger than the sum of its proper divisors (1).

640680440329 is an equidigital number, since it uses as much as digits as its factorization.

640680440329 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 995328, while the sum is 46.

The spelling of 640680440329 in words is "six hundred forty billion, six hundred eighty million, four hundred forty thousand, three hundred twenty-nine".