640681340471 has 2 divisors, whose sum is σ = 640681340472. Its totient is φ = 640681340470.

The previous prime is 640681340423. The next prime is 640681340477. The reversal of 640681340471 is 174043186046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640681340471 - 2¹⁰ = 640681339447 is a prime.

It is a super-3 number, since 3×640681340471³ (a number of 36 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640681340477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320340670235 + 320340670236.

It is an arithmetic number, because the mean of its divisors is an integer number (320340670236).

Almost surely, 2^640681340471 is an apocalyptic number.

640681340471 is a deficient number, since it is larger than the sum of its proper divisors (1).

640681340471 is an equidigital number, since it uses as much as digits as its factorization.

640681340471 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 387072, while the sum is 44.

The spelling of 640681340471 in words is "six hundred forty billion, six hundred eighty-one million, three hundred forty thousand, four hundred seventy-one".