644457 has 16 divisors (see below), whose sum is σ = 956160. Its totient is φ = 382800.

The previous prime is 644447. The next prime is 644489. The reversal of 644457 is 754446.

It is not a de Polignac number, because 644457 - 2⁸ = 644201 is a prime.

644457 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (644447) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1782 + ... + 2112.

It is an arithmetic number, because the mean of its divisors is an integer number (59760).

2⁶⁴⁴⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

644457 is a deficient number, since it is larger than the sum of its proper divisors (311703).

644457 is a wasteful number, since it uses less digits than its factorization.

644457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404.

The product of its digits is 13440, while the sum is 30.

The square root of 644457 is about 802.7807919974. The cubic root of 644457 is about 86.3769732446.

The spelling of 644457 in words is "six hundred forty-four thousand, four hundred fifty-seven".