644016739 has 4 divisors (see below), whose sum is σ = 645426424. Its totient is φ = 642607056.

The previous prime is 644016733. The next prime is 644016757. The reversal of 644016739 is 937610446.

644016739 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.

It is a cyclic number.

It is not a de Polignac number, because 644016739 - 2²⁷ = 509799011 is a prime.

It is a super-2 number, since 2×644016739² = 829515120224388242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644016733) 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, 704157 + ... + 705070.

It is an arithmetic number, because the mean of its divisors is an integer number (161356606).

Almost surely, 2^644016739 is an apocalyptic number.

644016739 is a deficient number, since it is larger than the sum of its proper divisors (1409685).

644016739 is a wasteful number, since it uses less digits than its factorization.

644016739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1409684.

The product of its (nonzero) digits is 108864, while the sum is 40.

The square root of 644016739 is about 25377.4848832582. The cubic root of 644016739 is about 863.5729927846.

The spelling of 644016739 in words is "six hundred forty-four million, sixteen thousand, seven hundred thirty-nine".