640171906679 has 2 divisors, whose sum is σ = 640171906680. Its totient is φ = 640171906678.

The previous prime is 640171906667. The next prime is 640171906691. The reversal of 640171906679 is 976609171046.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (640171906667) and next prime (640171906691).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640171906679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640171906079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320085953339 + 320085953340.

It is an arithmetic number, because the mean of its divisors is an integer number (320085953340).

Almost surely, 2^640171906679 is an apocalyptic number.

640171906679 is a deficient number, since it is larger than the sum of its proper divisors (1).

640171906679 is an equidigital number, since it uses as much as digits as its factorization.

640171906679 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3429216, while the sum is 56.

The spelling of 640171906679 in words is "six hundred forty billion, one hundred seventy-one million, nine hundred six thousand, six hundred seventy-nine".