640469717 has 2 divisors, whose sum is σ = 640469718. Its totient is φ = 640469716.

The previous prime is 640469663. The next prime is 640469723. The reversal of 640469717 is 717964046.

640469717 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 534811876 + 105657841 = 23126^2 + 10279^2 .

It is a cyclic number.

It is not a de Polignac number, because 640469717 - 2²² = 636275413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640469737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320234858 + 320234859.

It is an arithmetic number, because the mean of its divisors is an integer number (320234859).

Almost surely, 2^640469717 is an apocalyptic number.

It is an amenable number.

640469717 is a deficient number, since it is larger than the sum of its proper divisors (1).

640469717 is an equidigital number, since it uses as much as digits as its factorization.

640469717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 254016, while the sum is 44.

The square root of 640469717 is about 25307.5031759358. The cubic root of 640469717 is about 861.9846524974.

The spelling of 640469717 in words is "six hundred forty million, four hundred sixty-nine thousand, seven hundred seventeen".