644896 has 24 divisors (see below), whose sum is σ = 1451520. Its totient is φ = 276288.

The previous prime is 644881. The next prime is 644899. The reversal of 644896 is 698446.

It is not an unprimeable number, because it can be changed into a prime (644899) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1216 + ... + 1663.

It is an arithmetic number, because the mean of its divisors is an integer number (60480).

2⁶⁴⁴⁸⁹⁶ is an apocalyptic number.

It is an amenable number.

644896 is an abundant number, since it is smaller than the sum of its proper divisors (806624).

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

644896 is a wasteful number, since it uses less digits than its factorization.

644896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2896 (or 2888 counting only the distinct ones).

The product of its digits is 41472, while the sum is 37.

The square root of 644896 is about 803.0541700284. The cubic root of 644896 is about 86.3965819407.

It can be divided in two parts, 644 and 896, that added together give a triangular number (1540 = T₅₅).

The spelling of 644896 in words is "six hundred forty-four thousand, eight hundred ninety-six".