644812 has 12 divisors (see below), whose sum is σ = 1289680. Its totient is φ = 276336.

The previous prime is 644801. The next prime is 644837. The reversal of 644812 is 218446.

644812 is an admirable number.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

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 3 ways as a sum of consecutive naturals, for example, 11487 + ... + 11542.

2⁶⁴⁴⁸¹² is an apocalyptic number.

It is an amenable number.

644812 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

644812 is a wasteful number, since it uses less digits than its factorization.

644812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23040 (or 23038 counting only the distinct ones).

The product of its digits is 1536, while the sum is 25.

The square root of 644812 is about 803.0018679928. The cubic root of 644812 is about 86.3928306237.

The spelling of 644812 in words is "six hundred forty-four thousand, eight hundred twelve".