645865859 has 2 divisors, whose sum is σ = 645865860. Its totient is φ = 645865858.

The previous prime is 645865789. The next prime is 645865889. The reversal of 645865859 is 958568546.

645865859 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645865859 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645865889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322932929 + 322932930.

It is an arithmetic number, because the mean of its divisors is an integer number (322932930).

Almost surely, 2^645865859 is an apocalyptic number.

645865859 is a deficient number, since it is larger than the sum of its proper divisors (1).

645865859 is an equidigital number, since it uses as much as digits as its factorization.

645865859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368000, while the sum is 56.

The square root of 645865859 is about 25413.8910637470. The cubic root of 645865859 is about 864.3987084951.

The spelling of 645865859 in words is "six hundred forty-five million, eight hundred sixty-five thousand, eight hundred fifty-nine".