644478 has 16 divisors (see below), whose sum is σ = 1297296. Its totient is φ = 213440.

The previous prime is 644447. The next prime is 644489. The reversal of 644478 is 874446.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1168 + ... + 1628.

It is an arithmetic number, because the mean of its divisors is an integer number (81081).

2⁶⁴⁴⁴⁷⁸ is an apocalyptic number.

644478 is an abundant number, since it is smaller than the sum of its proper divisors (652818).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644478 is a wasteful number, since it uses less digits than its factorization.

644478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699.

The product of its digits is 21504, while the sum is 33.

The square root of 644478 is about 802.7938714265. The cubic root of 644478 is about 86.3779114488.

The spelling of 644478 in words is "six hundred forty-four thousand, four hundred seventy-eight".