640555067 has 2 divisors, whose sum is σ = 640555068. Its totient is φ = 640555066.

The previous prime is 640555061. The next prime is 640555081. The reversal of 640555067 is 760555046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640555067 - 2¹⁴ = 640538683 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640555067.

It is not a weakly prime, because it can be changed into another prime (640555061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320277533 + 320277534.

It is an arithmetic number, because the mean of its divisors is an integer number (320277534).

Almost surely, 2^640555067 is an apocalyptic number.

640555067 is a deficient number, since it is larger than the sum of its proper divisors (1).

640555067 is an equidigital number, since it uses as much as digits as its factorization.

640555067 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126000, while the sum is 38.

The square root of 640555067 is about 25309.1893785637. The cubic root of 640555067 is about 862.0229406061.

The spelling of 640555067 in words is "six hundred forty million, five hundred fifty-five thousand, sixty-seven".