644609 has 8 divisors (see below), whose sum is σ = 747648. Its totient is φ = 544320.

The previous prime is 644599. The next prime is 644617. The reversal of 644609 is 906446.

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

It is not a de Polignac number, because 644609 - 2⁴ = 644593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152 + ... + 1145.

It is an arithmetic number, because the mean of its divisors is an integer number (93456).

2⁶⁴⁴⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

644609 is a deficient number, since it is larger than the sum of its proper divisors (103039).

644609 is a wasteful number, since it uses less digits than its factorization.

644609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1375.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 644609 is about 802.8754573407. The cubic root of 644609 is about 86.3837635957.

The spelling of 644609 in words is "six hundred forty-four thousand, six hundred nine".