644335705 has 24 divisors (see below), whose sum is σ = 853629336. Its totient is φ = 464133120.

The previous prime is 644335687. The next prime is 644335729. The reversal of 644335705 is 507533446.

644335705 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 12 ways, for example, as 440874009 + 203461696 = 20997^2 + 14264^2 .

It is not a de Polignac number, because 644335705 - 2⁵ = 644335673 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 106317 + ... + 112213.

It is an arithmetic number, because the mean of its divisors is an integer number (35567889).

Almost surely, 2^644335705 is an apocalyptic number.

644335705 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644335705 is a deficient number, since it is larger than the sum of its proper divisors (209293631).

644335705 is a wasteful number, since it uses less digits than its factorization.

644335705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5997 (or 5956 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 37.

The square root of 644335705 is about 25383.7685342425. The cubic root of 644335705 is about 863.7155382312.

The spelling of 644335705 in words is "six hundred forty-four million, three hundred thirty-five thousand, seven hundred five".