644377409 has 16 divisors (see below), whose sum is σ = 709007040. Its totient is φ = 581995200.

The previous prime is 644377397. The next prime is 644377417. The reversal of 644377409 is 904773446.

It is a cyclic number.

It is not a de Polignac number, because 644377409 - 2¹⁶ = 644311873 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644377409.

It is not an unprimeable number, because it can be changed into a prime (644377309) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 172259 + ... + 175959.

It is an arithmetic number, because the mean of its divisors is an integer number (44312940).

Almost surely, 2^644377409 is an apocalyptic number.

It is an amenable number.

644377409 is a deficient number, since it is larger than the sum of its proper divisors (64629631).

644377409 is a wasteful number, since it uses less digits than its factorization.

644377409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4000.

The product of its (nonzero) digits is 508032, while the sum is 44.

The square root of 644377409 is about 25384.5899907798. The cubic root of 644377409 is about 863.7341722111.

The spelling of 644377409 in words is "six hundred forty-four million, three hundred seventy-seven thousand, four hundred nine".