645116551609 has 2 divisors, whose sum is σ = 645116551610. Its totient is φ = 645116551608.

The previous prime is 645116551601. The next prime is 645116551663. The reversal of 645116551609 is 906155611546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 565594243600 + 79522308009 = 752060^2 + 281997^2 .

It is a cyclic number.

It is not a de Polignac number, because 645116551609 - 2³ = 645116551601 is a prime.

It is not a weakly prime, because it can be changed into another prime (645116551601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322558275804 + 322558275805.

It is an arithmetic number, because the mean of its divisors is an integer number (322558275805).

Almost surely, 2^645116551609 is an apocalyptic number.

It is an amenable number.

645116551609 is a deficient number, since it is larger than the sum of its proper divisors (1).

645116551609 is an equidigital number, since it uses as much as digits as its factorization.

645116551609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972000, while the sum is 49.

The spelling of 645116551609 in words is "six hundred forty-five billion, one hundred sixteen million, five hundred fifty-one thousand, six hundred nine".