640964920643 has 2 divisors, whose sum is σ = 640964920644. Its totient is φ = 640964920642.

The previous prime is 640964920613. The next prime is 640964920657. The reversal of 640964920643 is 346029469046.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640964920643 - 2¹² = 640964916547 is a prime.

It is not a weakly prime, because it can be changed into another prime (640964920613) 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, 320482460321 + 320482460322.

It is an arithmetic number, because the mean of its divisors is an integer number (320482460322).

Almost surely, 2^640964920643 is an apocalyptic number.

640964920643 is a deficient number, since it is larger than the sum of its proper divisors (1).

640964920643 is an equidigital number, since it uses as much as digits as its factorization.

640964920643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6718464, while the sum is 53.

The spelling of 640964920643 in words is "six hundred forty billion, nine hundred sixty-four million, nine hundred twenty thousand, six hundred forty-three".