644690617 has 2 divisors, whose sum is σ = 644690618. Its totient is φ = 644690616.

The previous prime is 644690611. The next prime is 644690623. The reversal of 644690617 is 716096446.

It is a balanced prime because it is at equal distance from previous prime (644690611) and next prime (644690623).

It can be written as a sum of positive squares in only one way, i.e., 609892416 + 34798201 = 24696^2 + 5899^2 .

It is a cyclic number.

It is not a de Polignac number, because 644690617 - 2⁷ = 644690489 is a prime.

It is not a weakly prime, because it can be changed into another prime (644690611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322345308 + 322345309.

It is an arithmetic number, because the mean of its divisors is an integer number (322345309).

Almost surely, 2^644690617 is an apocalyptic number.

It is an amenable number.

644690617 is a deficient number, since it is larger than the sum of its proper divisors (1).

644690617 is an equidigital number, since it uses as much as digits as its factorization.

644690617 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 644690617 is about 25390.7584959568. The cubic root of 644690617 is about 863.8740926104.

The spelling of 644690617 in words is "six hundred forty-four million, six hundred ninety thousand, six hundred seventeen".