644523 has 8 divisors (see below), whose sum is σ = 937536. Its totient is φ = 390600.

The previous prime is 644519. The next prime is 644531. The reversal of 644523 is 325446.

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

It is not a de Polignac number, because 644523 - 2² = 644519 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 644493 and 644502.

It is not an unprimeable number, because it can be changed into a prime (644513) 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, 9733 + ... + 9798.

It is an arithmetic number, because the mean of its divisors is an integer number (117192).

2⁶⁴⁴⁵²³ is an apocalyptic number.

644523 is a deficient number, since it is larger than the sum of its proper divisors (293013).

644523 is a wasteful number, since it uses less digits than its factorization.

644523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19545.

The product of its digits is 2880, while the sum is 24.

The square root of 644523 is about 802.8218980571. The cubic root of 644523 is about 86.3799218177.

Adding to 644523 its reverse (325446), we get a palindrome (969969).

The spelling of 644523 in words is "six hundred forty-four thousand, five hundred twenty-three".