643305600403261 has 2 divisors, whose sum is σ = 643305600403262. Its totient is φ = 643305600403260.

The previous prime is 643305600403181. The next prime is 643305600403303. The reversal of 643305600403261 is 162304006503346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 352532543222500 + 290773057180761 = 18775850^2 + 17052069^2 .

It is a cyclic number.

It is not a de Polignac number, because 643305600403261 - 2²³ = 643305592014653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643305600503261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321652800201630 + 321652800201631.

It is an arithmetic number, because the mean of its divisors is an integer number (321652800201631).

Almost surely, 2^{643305600403261} is an apocalyptic number.

It is an amenable number.

643305600403261 is a deficient number, since it is larger than the sum of its proper divisors (1).

643305600403261 is an equidigital number, since it uses as much as digits as its factorization.

643305600403261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 933120, while the sum is 43.

The spelling of 643305600403261 in words is "six hundred forty-three trillion, three hundred five billion, six hundred million, four hundred three thousand, two hundred sixty-one".