644530 has 8 divisors (see below), whose sum is σ = 1160172. Its totient is φ = 257808.

The previous prime is 644519. The next prime is 644531. The reversal of 644530 is 35446.

It can be written as a sum of positive squares in 2 ways, for example, as 522729 + 121801 = 723^2 + 349^2 .

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

It is not an unprimeable number, because it can be changed into a prime (644531) by changing a digit.

644530 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 32217 + ... + 32236.

2⁶⁴⁴⁵³⁰ is an apocalyptic number.

644530 is a deficient number, since it is larger than the sum of its proper divisors (515642).

644530 is a wasteful number, since it uses less digits than its factorization.

644530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64460.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 644530 is about 802.8262576672. The cubic root of 644530 is about 86.3802345333.

Adding to 644530 its reverse (35446), we get a palindrome (679976).

The spelling of 644530 in words is "six hundred forty-four thousand, five hundred thirty".