645738757 has 2 divisors, whose sum is σ = 645738758. Its totient is φ = 645738756.

The previous prime is 645738749. The next prime is 645738767. The reversal of 645738757 is 757837546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 332661121 + 313077636 = 18239^2 + 17694^2 .

It is a cyclic number.

It is not a de Polignac number, because 645738757 - 2³ = 645738749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645738707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322869378 + 322869379.

It is an arithmetic number, because the mean of its divisors is an integer number (322869379).

Almost surely, 2^645738757 is an apocalyptic number.

It is an amenable number.

645738757 is a deficient number, since it is larger than the sum of its proper divisors (1).

645738757 is an equidigital number, since it uses as much as digits as its factorization.

645738757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4939200, while the sum is 52.

The square root of 645738757 is about 25411.3903004145. The cubic root of 645738757 is about 864.3420021833.

The spelling of 645738757 in words is "six hundred forty-five million, seven hundred thirty-eight thousand, seven hundred fifty-seven".