640907 has 2 divisors, whose sum is σ = 640908. Its totient is φ = 640906.

The previous prime is 640901. The next prime is 640919. The reversal of 640907 is 709046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640907 - 2⁴ = 640891 is a prime.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640907.

It is not a weakly prime, because it can be changed into another prime (640901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320453 + 320454.

It is an arithmetic number, because the mean of its divisors is an integer number (320454).

2⁶⁴⁰⁹⁰⁷ is an apocalyptic number.

640907 is a deficient number, since it is larger than the sum of its proper divisors (1).

640907 is an equidigital number, since it uses as much as digits as its factorization.

640907 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 640907 is about 800.5666743001. The cubic root of 640907 is about 86.2180782241.

The spelling of 640907 in words is "six hundred forty thousand, nine hundred seven".