644830 has 8 divisors (see below), whose sum is σ = 1160712. Its totient is φ = 257928.

The previous prime is 644801. The next prime is 644837. The reversal of 644830 is 38446.

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

It is a junction number, because it is equal to n+sod(n) for n = 644795 and 644804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644837) by changing a digit.

644830 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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32232 + ... + 32251.

It is an arithmetic number, because the mean of its divisors is an integer number (145089).

2⁶⁴⁴⁸³⁰ is an apocalyptic number.

644830 is a deficient number, since it is larger than the sum of its proper divisors (515882).

644830 is a wasteful number, since it uses less digits than its factorization.

644830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64490.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 644830 is about 803.0130758587. The cubic root of 644830 is about 86.3936345047.

The spelling of 644830 in words is "six hundred forty-four thousand, eight hundred thirty".