644633607 has 4 divisors (see below), whose sum is σ = 859511480. Its totient is φ = 429755736.

The previous prime is 644633603. The next prime is 644633629. The reversal of 644633607 is 706336446.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 644633607 - 2² = 644633603 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 (644633603) 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 3 ways as a sum of consecutive naturals, for example, 107438932 + ... + 107438937.

It is an arithmetic number, because the mean of its divisors is an integer number (214877870).

Almost surely, 2^644633607 is an apocalyptic number.

644633607 is a deficient number, since it is larger than the sum of its proper divisors (214877873).

644633607 is a wasteful number, since it uses less digits than its factorization.

644633607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214877872.

The product of its (nonzero) digits is 217728, while the sum is 39.

The square root of 644633607 is about 25389.6358185776. The cubic root of 644633607 is about 863.8486277272.

The spelling of 644633607 in words is "six hundred forty-four million, six hundred thirty-three thousand, six hundred seven".