644310761 has 12 divisors (see below), whose sum is σ = 687975948. Its totient is φ = 603278592.

The previous prime is 644310757. The next prime is 644310769. The reversal of 644310761 is 167013446.

It can be written as a sum of positive squares in 6 ways, for example, as 410832361 + 233478400 = 20269^2 + 15280^2 .

It is not a de Polignac number, because 644310761 - 2² = 644310757 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644310769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 51275 + ... + 62591.

It is an arithmetic number, because the mean of its divisors is an integer number (57331329).

Almost surely, 2^644310761 is an apocalyptic number.

It is an amenable number.

644310761 is a deficient number, since it is larger than the sum of its proper divisors (43665187).

644310761 is a wasteful number, since it uses less digits than its factorization.

644310761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11548 (or 11531 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 32.

The square root of 644310761 is about 25383.2771918836. The cubic root of 644310761 is about 863.7043924893.

The spelling of 644310761 in words is "six hundred forty-four million, three hundred ten thousand, seven hundred sixty-one".