644268 has 24 divisors (see below), whose sum is σ = 1533168. Its totient is φ = 210496.

The previous prime is 644261. The next prime is 644291. The reversal of 644268 is 862446.

644268 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a d-powerful number, because it can be written as 6⁵ + 4 + 2¹⁹ + 4⁸ + 6⁶ + 8 .

It is a nialpdrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (644261) by changing a digit.

644268 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 130 + ... + 1142.

It is an arithmetic number, because the mean of its divisors is an integer number (63882).

2⁶⁴⁴²⁶⁸ is an apocalyptic number.

It is an amenable number.

644268 is an abundant number, since it is smaller than the sum of its proper divisors (888900).

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

644268 is a wasteful number, since it uses less digits than its factorization.

644268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1073 (or 1071 counting only the distinct ones).

The product of its digits is 9216, while the sum is 30.

The square root of 644268 is about 802.6630675445. The cubic root of 644268 is about 86.3685284898.

The spelling of 644268 in words is "six hundred forty-four thousand, two hundred sixty-eight".