645738749 has 2 divisors, whose sum is σ = 645738750. Its totient is φ = 645738748.
The previous prime is 645738707. The next prime is 645738757. The reversal of 645738749 is 947837546.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 629658649 + 16080100 = 25093^2 + 4010^2 .
It is a cyclic number.
It is not a de Polignac number, because 645738749 - 28 = 645738493 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 645738749.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (645438749) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322869374 + 322869375.
It is an arithmetic number, because the mean of its divisors is an integer number (322869375).
Almost surely, 2645738749 is an apocalyptic number.
It is an amenable number.
645738749 is a deficient number, since it is larger than the sum of its proper divisors (1).
645738749 is an equidigital number, since it uses as much as digits as its factorization.
645738749 is an evil number, because the sum of its binary digits is even.
The product of its digits is 5080320, while the sum is 53.
The square root of 645738749 is about 25411.3901430048. The cubic root of 645738749 is about 864.3419986139.
The spelling of 645738749 in words is "six hundred forty-five million, seven hundred thirty-eight thousand, seven hundred forty-nine".
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