644427 has 24 divisors (see below), whose sum is σ = 1089504. Its totient is φ = 359424.

The previous prime is 644411. The next prime is 644431. The reversal of 644427 is 724446.

It is not a de Polignac number, because 644427 - 2⁴ = 644411 is a prime.

Its product of digits (5376) is a multiple of the sum of its prime divisors (256).

It is a self number, because there is not a number n which added to its sum of digits gives 644427.

It is not an unprimeable number, because it can be changed into a prime (644447) 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 23 ways as a sum of consecutive naturals, for example, 3243 + ... + 3435.

It is an arithmetic number, because the mean of its divisors is an integer number (45396).

2⁶⁴⁴⁴²⁷ is an apocalyptic number.

644427 is a deficient number, since it is larger than the sum of its proper divisors (445077).

644427 is a wasteful number, since it uses less digits than its factorization.

644427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259 (or 256 counting only the distinct ones).

The product of its digits is 5376, while the sum is 27.

The square root of 644427 is about 802.7621067290. The cubic root of 644427 is about 86.3756329176.

The spelling of 644427 in words is "six hundred forty-four thousand, four hundred twenty-seven".