644824013 has 4 divisors (see below), whose sum is σ = 654448320. Its totient is φ = 635199708.

The previous prime is 644824009. The next prime is 644824043. The reversal of 644824013 is 310428446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644824013 - 2² = 644824009 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 (644824043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4812053 + ... + 4812186.

It is an arithmetic number, because the mean of its divisors is an integer number (163612080).

Almost surely, 2^644824013 is an apocalyptic number.

It is an amenable number.

644824013 is a deficient number, since it is larger than the sum of its proper divisors (9624307).

644824013 is an equidigital number, since it uses as much as digits as its factorization.

644824013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9624306.

The product of its (nonzero) digits is 18432, while the sum is 32.

The square root of 644824013 is about 25393.3852213524. The cubic root of 644824013 is about 863.9336712663.

The spelling of 644824013 in words is "six hundred forty-four million, eight hundred twenty-four thousand, thirteen".