645739049 has 2 divisors, whose sum is σ = 645739050. Its totient is φ = 645739048.

The previous prime is 645738937. The next prime is 645739051. The reversal of 645739049 is 940937546.

It is a happy number.

645739049 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., 344473600 + 301265449 = 18560^2 + 17357^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645739049 is a prime.

It is a Sophie Germain prime.

Together with 645739051, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 645738994 and 645739012.

It is not a weakly prime, because it can be changed into another prime (645739079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322869524 + 322869525.

It is an arithmetic number, because the mean of its divisors is an integer number (322869525).

Almost surely, 2^645739049 is an apocalyptic number.

It is an amenable number.

645739049 is a deficient number, since it is larger than the sum of its proper divisors (1).

645739049 is an equidigital number, since it uses as much as digits as its factorization.

645739049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 816480, while the sum is 47.

The square root of 645739049 is about 25411.3960458689. The cubic root of 645739049 is about 864.3421324670.

The spelling of 645739049 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, forty-nine".