1644444566789 has 8 divisors (see below), whose sum is σ = 1651718983320. Its totient is φ = 1637170963200.

The previous prime is 1644444566761. The next prime is 1644444566813. The reversal of 1644444566789 is 9876654444461.

It can be written as a sum of positive squares in 4 ways, for example, as 1436857716100 + 207586850689 = 1198690^2 + 455617^2 .

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 1644444566789 - 2²⁸ = 1644176131333 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 (1644444526789) 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, 4047449 + ... + 4435169.

It is an arithmetic number, because the mean of its divisors is an integer number (206464872915).

Almost surely, 2^{1644444566789} is an apocalyptic number.

It is an amenable number.

1644444566789 is a deficient number, since it is larger than the sum of its proper divisors (7274416531).

1644444566789 is a wasteful number, since it uses less digits than its factorization.

1644444566789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406471.

The product of its digits is 557383680, while the sum is 68.

The spelling of 1644444566789 in words is "one trillion, six hundred forty-four billion, four hundred forty-four million, five hundred sixty-six thousand, seven hundred eighty-nine".