644504393 has 8 divisors (see below), whose sum is σ = 697680648. Its totient is φ = 591842304.

The previous prime is 644504389. The next prime is 644504401. The reversal of 644504393 is 393405446.

It is a happy number.

644504393 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 96569929 + 547934464 = 9827^2 + 23408^2 .

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 644504393 - 2² = 644504389 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644504303) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 125930 + ... + 130947.

It is an arithmetic number, because the mean of its divisors is an integer number (87210081).

Almost surely, 2^644504393 is an apocalyptic number.

It is an amenable number.

644504393 is a deficient number, since it is larger than the sum of its proper divisors (53176255).

644504393 is a wasteful number, since it uses less digits than its factorization.

644504393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257083.

The product of its (nonzero) digits is 155520, while the sum is 38.

The square root of 644504393 is about 25387.0910700694. The cubic root of 644504393 is about 863.7909056381.

The spelling of 644504393 in words is "six hundred forty-four million, five hundred four thousand, three hundred ninety-three".