645863717 has 2 divisors, whose sum is σ = 645863718. Its totient is φ = 645863716.

The previous prime is 645863689. The next prime is 645863767. The reversal of 645863717 is 717368546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 615734596 + 30129121 = 24814^2 + 5489^2 .

It is a cyclic number.

It is not a de Polignac number, because 645863717 - 2⁸ = 645863461 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645863767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322931858 + 322931859.

It is an arithmetic number, because the mean of its divisors is an integer number (322931859).

Almost surely, 2^645863717 is an apocalyptic number.

It is an amenable number.

645863717 is a deficient number, since it is larger than the sum of its proper divisors (1).

645863717 is an equidigital number, since it uses as much as digits as its factorization.

645863717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 846720, while the sum is 47.

The square root of 645863717 is about 25413.8489214050. The cubic root of 645863717 is about 864.3977529076.

The spelling of 645863717 in words is "six hundred forty-five million, eight hundred sixty-three thousand, seven hundred seventeen".