644728827445 has 8 divisors (see below), whose sum is σ = 774172782936. Its totient is φ = 515450935296.

The previous prime is 644728827443. The next prime is 644728827487. The reversal of 644728827445 is 544728827446.

644728827445 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 32732408241 + 611996419204 = 180921^2 + 782302^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644728827445 - 2¹ = 644728827443 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644728827443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41507292 + ... + 41522821.

It is an arithmetic number, because the mean of its divisors is an integer number (96771597867).

Almost surely, 2^644728827445 is an apocalyptic number.

It is an amenable number.

644728827445 is a deficient number, since it is larger than the sum of its proper divisors (129443955491).

644728827445 is a wasteful number, since it uses less digits than its factorization.

644728827445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83031671.

The product of its digits is 96337920, while the sum is 61.

Subtracting from 644728827445 its reverse (544728827446), we obtain a palindrome (99999999999).

The spelling of 644728827445 in words is "six hundred forty-four billion, seven hundred twenty-eight million, eight hundred twenty-seven thousand, four hundred forty-five".