644859 has 12 divisors (see below), whose sum is σ = 940056. Its totient is φ = 425952.

The previous prime is 644857. The next prime is 644863. The reversal of 644859 is 958446.

644859 is a `hidden beast` number, since 644 + 8 + 5 + 9 = 666.

It is not a de Polignac number, because 644859 - 2¹ = 644857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 972 + ... + 1494.

It is an arithmetic number, because the mean of its divisors is an integer number (78338).

2⁶⁴⁴⁸⁵⁹ is an apocalyptic number.

644859 is a deficient number, since it is larger than the sum of its proper divisors (295197).

644859 is a wasteful number, since it uses less digits than its factorization.

644859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 666 (or 663 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 644859 is about 803.0311326468. The cubic root of 644859 is about 86.3949296150.

The spelling of 644859 in words is "six hundred forty-four thousand, eight hundred fifty-nine".