644507135 has 4 divisors (see below), whose sum is σ = 773408568. Its totient is φ = 515605704.

The previous prime is 644507089. The next prime is 644507141. The reversal of 644507135 is 531705446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 531705446 = 2 ⋅265852723.

It is a cyclic number.

It is not a de Polignac number, because 644507135 - 2¹⁰ = 644506111 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644507095 and 644507104.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64450709 + ... + 64450718.

It is an arithmetic number, because the mean of its divisors is an integer number (193352142).

Almost surely, 2^644507135 is an apocalyptic number.

644507135 is a deficient number, since it is larger than the sum of its proper divisors (128901433).

644507135 is a wasteful number, since it uses less digits than its factorization.

644507135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128901432.

The product of its (nonzero) digits is 50400, while the sum is 35.

The square root of 644507135 is about 25387.1450738361. The cubic root of 644507135 is about 863.7921306162.

The spelling of 644507135 in words is "six hundred forty-four million, five hundred seven thousand, one hundred thirty-five".