644730 has 16 divisors (see below), whose sum is σ = 1547424. Its totient is φ = 171920.

The previous prime is 644729. The next prime is 644731. The reversal of 644730 is 37446.

It is an interprime number because it is at equal distance from previous prime (644729) and next prime (644731).

It is a self number, because there is not a number n which added to its sum of digits gives 644730.

It is not an unprimeable number, because it can be changed into a prime (644731) 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, 10716 + ... + 10775.

It is an arithmetic number, because the mean of its divisors is an integer number (96714).

2⁶⁴⁴⁷³⁰ is an apocalyptic number.

644730 is an abundant number, since it is smaller than the sum of its proper divisors (902694).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644730 is a wasteful number, since it uses less digits than its factorization.

644730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21501.

The product of its (nonzero) digits is 2016, while the sum is 24.

The square root of 644730 is about 802.9508079577. The cubic root of 644730 is about 86.3891683095.

The spelling of 644730 in words is "six hundred forty-four thousand, seven hundred thirty".