644716069 has 4 divisors (see below), whose sum is σ = 655643520. Its totient is φ = 633788620.

The previous prime is 644716067. The next prime is 644716073. The reversal of 644716069 is 960617446.

644716069 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 644716069 - 2¹ = 644716067 is a prime.

It is a super-2 number, since 2×644716069² = 831317619253625522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644716067) 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, 5463637 + ... + 5463754.

It is an arithmetic number, because the mean of its divisors is an integer number (163910880).

Almost surely, 2^644716069 is an apocalyptic number.

It is an amenable number.

644716069 is a deficient number, since it is larger than the sum of its proper divisors (10927451).

644716069 is a wasteful number, since it uses less digits than its factorization.

644716069 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10927450.

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 644716069 is about 25391.2596969902. The cubic root of 644716069 is about 863.8854608716.

The spelling of 644716069 in words is "six hundred forty-four million, seven hundred sixteen thousand, sixty-nine".