644626542645 has 32 divisors (see below), whose sum is σ = 1150461959040. Its totient is φ = 342463057920.

The previous prime is 644626542617. The next prime is 644626542653. The reversal of 644626542645 is 546245626446.

644626542645 is a `hidden beast` number, since 6 + 4 + 4 + 626 + 5 + 4 + 2 + 6 + 4 + 5 = 666.

It is not a de Polignac number, because 644626542645 - 2³⁸ = 369748635701 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644626542591 and 644626542600.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 9255211 + ... + 9324600.

It is an arithmetic number, because the mean of its divisors is an integer number (35951936220).

Almost surely, 2^644626542645 is an apocalyptic number.

It is an amenable number.

644626542645 is a deficient number, since it is larger than the sum of its proper divisors (505835416395).

644626542645 is a wasteful number, since it uses less digits than its factorization.

644626542645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18580082 (or 18580076 counting only the distinct ones).

The product of its digits is 33177600, while the sum is 54.

The spelling of 644626542645 in words is "six hundred forty-four billion, six hundred twenty-six million, five hundred forty-two thousand, six hundred forty-five".