644717 has 2 divisors, whose sum is σ = 644718. Its totient is φ = 644716.

The previous prime is 644701. The next prime is 644729. The reversal of 644717 is 717446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 546121 + 98596 = 739^2 + 314^2 .

It is a cyclic number.

It is not a de Polignac number, because 644717 - 2⁴ = 644701 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644717.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644717.

It is not a weakly prime, because it can be changed into another prime (644747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322358 + 322359.

It is an arithmetic number, because the mean of its divisors is an integer number (322359).

2⁶⁴⁴⁷¹⁷ is an apocalyptic number.

It is an amenable number.

644717 is a deficient number, since it is larger than the sum of its proper divisors (1).

644717 is an equidigital number, since it uses as much as digits as its factorization.

644717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4704, while the sum is 29.

The square root of 644717 is about 802.9427127759. The cubic root of 644717 is about 86.3885876702.

The spelling of 644717 in words is "six hundred forty-four thousand, seven hundred seventeen".