645540646109 has 2 divisors, whose sum is σ = 645540646110. Its totient is φ = 645540646108.

The previous prime is 645540646067. The next prime is 645540646133. The reversal of 645540646109 is 901646045546.

645540646109 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., 568893062500 + 76647583609 = 754250^2 + 276853^2 .

It is a cyclic number.

It is not a de Polignac number, because 645540646109 - 2²⁴ = 645523868893 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645540646189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322770323054 + 322770323055.

It is an arithmetic number, because the mean of its divisors is an integer number (322770323055).

Almost surely, 2^645540646109 is an apocalyptic number.

It is an amenable number.

645540646109 is a deficient number, since it is larger than the sum of its proper divisors (1).

645540646109 is an equidigital number, since it uses as much as digits as its factorization.

645540646109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3110400, while the sum is 50.

The spelling of 645540646109 in words is "six hundred forty-five billion, five hundred forty million, six hundred forty-six thousand, one hundred nine".