644345 has 16 divisors (see below), whose sum is σ = 870912. Its totient is φ = 454080.

The previous prime is 644341. The next prime is 644353. The reversal of 644345 is 543446.

It is not a de Polignac number, because 644345 - 2² = 644341 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644341) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1280 + ... + 1710.

It is an arithmetic number, because the mean of its divisors is an integer number (54432).

2⁶⁴⁴³⁴⁵ is an apocalyptic number.

644345 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644345 is a deficient number, since it is larger than the sum of its proper divisors (226567).

644345 is a wasteful number, since it uses less digits than its factorization.

644345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472.

The product of its digits is 5760, while the sum is 26.

The square root of 644345 is about 802.7110314428. The cubic root of 644345 is about 86.3719691448.

It can be divided in two parts, 644 and 345, that added together give a palindrome (989).

The spelling of 644345 in words is "six hundred forty-four thousand, three hundred forty-five".