644983 has 4 divisors (see below), whose sum is σ = 652320. Its totient is φ = 637648.

The previous prime is 644977. The next prime is 644999. The reversal of 644983 is 389446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 389446 = 2 ⋅194723.

It is a cyclic number.

It is not a de Polignac number, because 644983 - 2⁵ = 644951 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 (644923) 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, 3535 + ... + 3712.

It is an arithmetic number, because the mean of its divisors is an integer number (163080).

2⁶⁴⁴⁹⁸³ is an apocalyptic number.

644983 is a deficient number, since it is larger than the sum of its proper divisors (7337).

644983 is an equidigital number, since it uses as much as digits as its factorization.

644983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7336.

The product of its digits is 20736, while the sum is 34.

The square root of 644983 is about 803.1083364030. The cubic root of 644983 is about 86.4004668899.

The spelling of 644983 in words is "six hundred forty-four thousand, nine hundred eighty-three".