645643808065 has 24 divisors (see below), whose sum is σ = 803937754368. Its totient is φ = 497258910720.

The previous prime is 645643808057. The next prime is 645643808093. The reversal of 645643808065 is 560808346546.

645643808065 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 645643808065 - 2³ = 645643808057 is a prime.

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645643807997 and 645643808015.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5717682 + ... + 5829508.

It is an arithmetic number, because the mean of its divisors is an integer number (33497406432).

Almost surely, 2^645643808065 is an apocalyptic number.

It is an amenable number.

645643808065 is a deficient number, since it is larger than the sum of its proper divisors (158293946303).

645643808065 is a wasteful number, since it uses less digits than its factorization.

645643808065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112249 (or 112056 counting only the distinct ones).

The product of its (nonzero) digits is 16588800, while the sum is 55.

The spelling of 645643808065 in words is "six hundred forty-five billion, six hundred forty-three million, eight hundred eight thousand, sixty-five".