644878 has 16 divisors (see below), whose sum is σ = 1103760. Its totient is φ = 279936.

The previous prime is 644869. The next prime is 644881. The reversal of 644878 is 878446.

It is a congruent number.

It is an unprimeable number.

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, 288 + ... + 1171.

It is an arithmetic number, because the mean of its divisors is an integer number (68985).

2⁶⁴⁴⁸⁷⁸ is an apocalyptic number.

644878 is a deficient number, since it is larger than the sum of its proper divisors (458882).

644878 is a wasteful number, since it uses less digits than its factorization.

644878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1491.

The product of its digits is 43008, while the sum is 37.

The square root of 644878 is about 803.0429627361. The cubic root of 644878 is about 86.3957781145.

The spelling of 644878 in words is "six hundred forty-four thousand, eight hundred seventy-eight".