644287 has 4 divisors (see below), whose sum is σ = 736336. Its totient is φ = 552240.

The previous prime is 644261. The next prime is 644291. The reversal of 644287 is 782446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644287 - 2⁷ = 644159 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 (644227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46014 + ... + 46027.

It is an arithmetic number, because the mean of its divisors is an integer number (184084).

2⁶⁴⁴²⁸⁷ is an apocalyptic number.

644287 is a deficient number, since it is larger than the sum of its proper divisors (92049).

644287 is an equidigital number, since it uses as much as digits as its factorization.

644287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92048.

The product of its digits is 10752, while the sum is 31.

The square root of 644287 is about 802.6749030585. The cubic root of 644287 is about 86.3693775080.

The spelling of 644287 in words is "six hundred forty-four thousand, two hundred eighty-seven".