645518878687 has 2 divisors, whose sum is σ = 645518878688. Its totient is φ = 645518878686.

The previous prime is 645518878681. The next prime is 645518878717. The reversal of 645518878687 is 786878815546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645518878687 - 2³ = 645518878679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645518878681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322759439343 + 322759439344.

It is an arithmetic number, because the mean of its divisors is an integer number (322759439344).

Almost surely, 2^645518878687 is an apocalyptic number.

645518878687 is a deficient number, since it is larger than the sum of its proper divisors (1).

645518878687 is an equidigital number, since it uses as much as digits as its factorization.

645518878687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 722534400, while the sum is 73.

The spelling of 645518878687 in words is "six hundred forty-five billion, five hundred eighteen million, eight hundred seventy-eight thousand, six hundred eighty-seven".