644004271 has 8 divisors (see below), whose sum is σ = 648867744. Its totient is φ = 639153120.

The previous prime is 644004241. The next prime is 644004299. The reversal of 644004271 is 172400446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644004271 - 2⁷ = 644004143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644004241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 119781 + ... + 125041.

It is an arithmetic number, because the mean of its divisors is an integer number (81108468).

Almost surely, 2^644004271 is an apocalyptic number.

644004271 is a deficient number, since it is larger than the sum of its proper divisors (4863473).

644004271 is a wasteful number, since it uses less digits than its factorization.

644004271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6161.

The product of its (nonzero) digits is 5376, while the sum is 28.

The square root of 644004271 is about 25377.2392312481. The cubic root of 644004271 is about 863.5674198976.

The spelling of 644004271 in words is "six hundred forty-four million, four thousand, two hundred seventy-one".