644722 has 16 divisors (see below), whose sum is σ = 1054872. Its totient is φ = 293760.

The previous prime is 644717. The next prime is 644729. The reversal of 644722 is 227446.

It can be written as a sum of positive squares in 4 ways, for example, as 259081 + 385641 = 509^2 + 621^2 .

It is not an unprimeable number, because it can be changed into a prime (644729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3472 + ... + 3652.

2⁶⁴⁴⁷²² is an apocalyptic number.

644722 is a deficient number, since it is larger than the sum of its proper divisors (410150).

644722 is a wasteful number, since it uses less digits than its factorization.

644722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333.

The product of its digits is 2688, while the sum is 25.

The square root of 644722 is about 802.9458263171. The cubic root of 644722 is about 86.3888109939.

The spelling of 644722 in words is "six hundred forty-four thousand, seven hundred twenty-two".