644871 has 8 divisors (see below), whose sum is σ = 880000. Its totient is φ = 419832.

The previous prime is 644869. The next prime is 644881. The reversal of 644871 is 178446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644871 - 2¹ = 644869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644801) 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, 2371 + ... + 2628.

It is an arithmetic number, because the mean of its divisors is an integer number (110000).

2⁶⁴⁴⁸⁷¹ is an apocalyptic number.

644871 is a deficient number, since it is larger than the sum of its proper divisors (235129).

644871 is a wasteful number, since it uses less digits than its factorization.

644871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5045.

The product of its digits is 5376, while the sum is 30.

The square root of 644871 is about 803.0386043024. The cubic root of 644871 is about 86.3954655113.

The spelling of 644871 in words is "six hundred forty-four thousand, eight hundred seventy-one".