644340565 has 8 divisors (see below), whose sum is σ = 843500448. Its totient is φ = 468611280.

The previous prime is 644340539. The next prime is 644340569. The reversal of 644340565 is 565043446.

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

It is not a de Polignac number, because 644340565 - 2¹¹ = 644338517 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 (644340569) 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, 5857587 + ... + 5857696.

It is an arithmetic number, because the mean of its divisors is an integer number (105437556).

Almost surely, 2^644340565 is an apocalyptic number.

It is an amenable number.

644340565 is a deficient number, since it is larger than the sum of its proper divisors (199159883).

644340565 is a wasteful number, since it uses less digits than its factorization.

644340565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11715299.

The product of its (nonzero) digits is 172800, while the sum is 37.

The square root of 644340565 is about 25383.8642645284. The cubic root of 644340565 is about 863.7177097943.

The spelling of 644340565 in words is "six hundred forty-four million, three hundred forty thousand, five hundred sixty-five".