645650207021 has 2 divisors, whose sum is σ = 645650207022. Its totient is φ = 645650207020.

The previous prime is 645650207011. The next prime is 645650207051. The reversal of 645650207021 is 120702056546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 525233572900 + 120416634121 = 724730^2 + 347011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645650207021 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 (645650207011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322825103510 + 322825103511.

It is an arithmetic number, because the mean of its divisors is an integer number (322825103511).

Almost surely, 2^645650207021 is an apocalyptic number.

It is an amenable number.

645650207021 is a deficient number, since it is larger than the sum of its proper divisors (1).

645650207021 is an equidigital number, since it uses as much as digits as its factorization.

645650207021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100800, while the sum is 38.

The spelling of 645650207021 in words is "six hundred forty-five billion, six hundred fifty million, two hundred seven thousand, twenty-one".