644360389 has 4 divisors (see below), whose sum is σ = 665146240. Its totient is φ = 623574540.

The previous prime is 644360377. The next prime is 644360399. The reversal of 644360389 is 983063446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644360389 - 2¹³ = 644352197 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 (644360359) 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, 10392879 + ... + 10392940.

It is an arithmetic number, because the mean of its divisors is an integer number (166286560).

Almost surely, 2^644360389 is an apocalyptic number.

It is an amenable number.

644360389 is a deficient number, since it is larger than the sum of its proper divisors (20785851).

644360389 is a wasteful number, since it uses less digits than its factorization.

644360389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20785850.

The product of its (nonzero) digits is 373248, while the sum is 43.

The square root of 644360389 is about 25384.2547458065. The cubic root of 644360389 is about 863.7265675140.

The spelling of 644360389 in words is "six hundred forty-four million, three hundred sixty thousand, three hundred eighty-nine".