644341361 has 4 divisors (see below), whose sum is σ = 682243812. Its totient is φ = 606438912.

The previous prime is 644341351. The next prime is 644341381. The reversal of 644341361 is 163143446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 366952336 + 277389025 = 19156^2 + 16655^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644341361 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644341331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18951200 + ... + 18951233.

It is an arithmetic number, because the mean of its divisors is an integer number (170560953).

Almost surely, 2^644341361 is an apocalyptic number.

It is an amenable number.

644341361 is a deficient number, since it is larger than the sum of its proper divisors (37902451).

644341361 is a wasteful number, since it uses less digits than its factorization.

644341361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37902450.

The product of its digits is 20736, while the sum is 32.

The square root of 644341361 is about 25383.8799437753. The cubic root of 644341361 is about 863.7180654649.

The spelling of 644341361 in words is "six hundred forty-four million, three hundred forty-one thousand, three hundred sixty-one".