644045540445 has 32 divisors (see below), whose sum is σ = 1181904368640. Its totient is φ = 332410599360.

The previous prime is 644045540407. The next prime is 644045540513. The reversal of 644045540445 is 544045540446.

644045540445 is a `hidden beast` number, since 64 + 4 + 0 + 4 + 5 + 540 + 4 + 45 = 666.

644045540445 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 644045540445 - 2⁷ = 644045540317 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 644045540445.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 76942714 + ... + 76951083.

It is an arithmetic number, because the mean of its divisors is an integer number (36934511520).

Almost surely, 2^644045540445 is an apocalyptic number.

It is an amenable number.

644045540445 is a deficient number, since it is larger than the sum of its proper divisors (537858828195).

644045540445 is a wasteful number, since it uses less digits than its factorization.

644045540445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153893842 (or 153893836 counting only the distinct ones).

The product of its (nonzero) digits is 3072000, while the sum is 45.

Subtracting from 644045540445 its reverse (544045540446), we obtain a palindrome (99999999999).

The spelling of 644045540445 in words is "six hundred forty-four billion, forty-five million, five hundred forty thousand, four hundred forty-five".