644645268745 has 16 divisors (see below), whose sum is σ = 814309577280. Its totient is φ = 488560766400.

The previous prime is 644645268727. The next prime is 644645268769. The reversal of 644645268745 is 547862546446.

It is not a de Polignac number, because 644645268745 - 2²¹ = 644643171593 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5603250 + ... + 5717140.

It is an arithmetic number, because the mean of its divisors is an integer number (50894348580).

Almost surely, 2^644645268745 is an apocalyptic number.

It is an amenable number.

644645268745 is a deficient number, since it is larger than the sum of its proper divisors (169664308535).

644645268745 is a wasteful number, since it uses less digits than its factorization.

644645268745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173496.

The product of its digits is 154828800, while the sum is 61.

The spelling of 644645268745 in words is "six hundred forty-four billion, six hundred forty-five million, two hundred sixty-eight thousand, seven hundred forty-five".