644043753125 has 12 divisors (see below), whose sum is σ = 805003171812. Its totient is φ = 515235000000.

The previous prime is 644043753121. The next prime is 644043753139. The reversal of 644043753125 is 521357340446.

It can be written as a sum of positive squares in 6 ways, for example, as 471587105284 + 172456647841 = 686722^2 + 415279^2 .

It is not a de Polignac number, because 644043753125 - 2² = 644043753121 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 (644043753121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 103043876 + ... + 103050125.

It is an arithmetic number, because the mean of its divisors is an integer number (67083597651).

Almost surely, 2^644043753125 is an apocalyptic number.

It is an amenable number.

644043753125 is a deficient number, since it is larger than the sum of its proper divisors (160959418687).

644043753125 is an frugal number, since it uses more digits than its factorization.

644043753125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206094026 (or 206094006 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 44.

The spelling of 644043753125 in words is "six hundred forty-four billion, forty-three million, seven hundred fifty-three thousand, one hundred twenty-five".