645591983985 has 96 divisors (see below), whose sum is σ = 1261113235200. Its totient is φ = 303137911296.

The previous prime is 645591983983. The next prime is 645591984007. The reversal of 645591983985 is 589389195546.

645591983985 is a `hidden beast` number, since 6 + 45 + 5 + 9 + 198 + 398 + 5 = 666.

645591983985 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 645591983985 - 2¹ = 645591983983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645591983983) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4627054 + ... + 4764536.

It is an arithmetic number, because the mean of its divisors is an integer number (13136596200).

Almost surely, 2^645591983985 is an apocalyptic number.

645591983985 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

645591983985 is a deficient number, since it is larger than the sum of its proper divisors (615521251215).

645591983985 is a wasteful number, since it uses less digits than its factorization.

645591983985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137879 (or 137876 counting only the distinct ones).

The product of its digits is 419904000, while the sum is 72.

The spelling of 645591983985 in words is "six hundred forty-five billion, five hundred ninety-one million, nine hundred eighty-three thousand, nine hundred eighty-five".