644260 has 12 divisors (see below), whose sum is σ = 1352988. Its totient is φ = 257696.

The previous prime is 644257. The next prime is 644261. The reversal of 644260 is 62446.

It can be written as a sum of positive squares in 2 ways, for example, as 443556 + 200704 = 666^2 + 448^2 .

It is a d-powerful number, because it can be written as 6⁵ + 4 + 2¹⁹ + 4⁸ + 6⁶ + 0 .

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.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16087 + ... + 16126.

It is an arithmetic number, because the mean of its divisors is an integer number (112749).

2⁶⁴⁴²⁶⁰ is an apocalyptic number.

It is an amenable number.

644260 is an abundant number, since it is smaller than the sum of its proper divisors (708728).

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

644260 is a wasteful number, since it uses less digits than its factorization.

644260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32222 (or 32220 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 644260 is about 802.6580841180. The cubic root of 644260 is about 86.3681710034.

The spelling of 644260 in words is "six hundred forty-four thousand, two hundred sixty".