644663013 has 4 divisors (see below), whose sum is σ = 859550688. Its totient is φ = 429775340.

The previous prime is 644663003. The next prime is 644663017. The reversal of 644663013 is 310366446.

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 644663013 - 2⁵ = 644662981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644663017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107443833 + ... + 107443838.

It is an arithmetic number, because the mean of its divisors is an integer number (214887672).

Almost surely, 2^644663013 is an apocalyptic number.

It is an amenable number.

644663013 is a deficient number, since it is larger than the sum of its proper divisors (214887675).

644663013 is a wasteful number, since it uses less digits than its factorization.

644663013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214887674.

The product of its (nonzero) digits is 31104, while the sum is 33.

The square root of 644663013 is about 25390.2149065344. The cubic root of 644663013 is about 863.8617628095.

The spelling of 644663013 in words is "six hundred forty-four million, six hundred sixty-three thousand, thirteen".