644425 has 12 divisors (see below), whose sum is σ = 809100. Its totient is φ = 509120.

The previous prime is 644411. The next prime is 644431. The reversal of 644425 is 524446.

644425 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 9216 + 635209 = 96^2 + 797^2 .

It is not a de Polignac number, because 644425 - 2⁷ = 644297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a self number, because there is not a number n which added to its sum of digits gives 644425.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3639 + ... + 3811.

It is an arithmetic number, because the mean of its divisors is an integer number (67425).

2⁶⁴⁴⁴²⁵ is an apocalyptic number.

It is an amenable number.

644425 is a deficient number, since it is larger than the sum of its proper divisors (164675).

644425 is a wasteful number, since it uses less digits than its factorization.

644425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332 (or 327 counting only the distinct ones).

The product of its digits is 3840, while the sum is 25.

The square root of 644425 is about 802.7608610290. The cubic root of 644425 is about 86.3755435610.

It can be divided in two parts, 64 and 4425, that added together give a square (4489 = 67²).

The spelling of 644425 in words is "six hundred forty-four thousand, four hundred twenty-five".