644493 has 4 divisors (see below), whose sum is σ = 859328. Its totient is φ = 429660.

The previous prime is 644491. The next prime is 644507. The reversal of 644493 is 394446.

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 not a de Polignac number, because 644493 - 2¹ = 644491 is a prime.

It is a D-number.

It is a Duffinian number.

644493 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 644493.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644493.

It is not an unprimeable number, because it can be changed into a prime (644491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107413 + ... + 107418.

It is an arithmetic number, because the mean of its divisors is an integer number (214832).

2⁶⁴⁴⁴⁹³ is an apocalyptic number.

It is an amenable number.

644493 is a deficient number, since it is larger than the sum of its proper divisors (214835).

644493 is a wasteful number, since it uses less digits than its factorization.

644493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214834.

The product of its digits is 10368, while the sum is 30.

The square root of 644493 is about 802.8032137454. The cubic root of 644493 is about 86.3785815821.

Subtracting from 644493 its reverse (394446), we obtain a cube (250047 = 63³).

The spelling of 644493 in words is "six hundred forty-four thousand, four hundred ninety-three".