644791417 has 2 divisors, whose sum is σ = 644791418. Its totient is φ = 644791416.

The previous prime is 644791397. The next prime is 644791421. The reversal of 644791417 is 714197446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644601321 + 190096 = 25389^2 + 436^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644791417 is a prime.

It is not a weakly prime, because it can be changed into another prime (644791517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322395708 + 322395709.

It is an arithmetic number, because the mean of its divisors is an integer number (322395709).

Almost surely, 2^644791417 is an apocalyptic number.

It is an amenable number.

644791417 is a deficient number, since it is larger than the sum of its proper divisors (1).

644791417 is an equidigital number, since it uses as much as digits as its factorization.

644791417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 43.

The square root of 644791417 is about 25392.7433925521. The cubic root of 644791417 is about 863.9191136734.

The spelling of 644791417 in words is "six hundred forty-four million, seven hundred ninety-one thousand, four hundred seventeen".