644138143 has 16 divisors (see below), whose sum is σ = 764148384. Its totient is φ = 536232960.

The previous prime is 644138071. The next prime is 644138147. The reversal of 644138143 is 341831446.

644138143 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 644138143 - 2¹³ = 644129951 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644138099 and 644138108.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644138147) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39630 + ... + 53467.

It is an arithmetic number, because the mean of its divisors is an integer number (47759274).

Almost surely, 2^644138143 is an apocalyptic number.

644138143 is a deficient number, since it is larger than the sum of its proper divisors (120010241).

644138143 is a wasteful number, since it uses less digits than its factorization.

644138143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93162.

The product of its digits is 27648, while the sum is 34.

The square root of 644138143 is about 25379.8767333492. The cubic root of 644138143 is about 863.6272536042.

Adding to 644138143 its reverse (341831446), we get a palindrome (985969589).

The spelling of 644138143 in words is "six hundred forty-four million, one hundred thirty-eight thousand, one hundred forty-three".