643954424459257 has 2 divisors, whose sum is σ = 643954424459258. Its totient is φ = 643954424459256.

The previous prime is 643954424459219. The next prime is 643954424459363. The reversal of 643954424459257 is 752954424459346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 643073859927801 + 880564531456 = 25358901^2 + 938384^2 .

It is a cyclic number.

It is not a de Polignac number, because 643954424459257 - 2²⁷ = 643954290241529 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643954424459257.

It is not a weakly prime, because it can be changed into another prime (643954424859257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321977212229628 + 321977212229629.

It is an arithmetic number, because the mean of its divisors is an integer number (321977212229629).

Almost surely, 2^{643954424459257} is an apocalyptic number.

It is an amenable number.

643954424459257 is a deficient number, since it is larger than the sum of its proper divisors (1).

643954424459257 is an equidigital number, since it uses as much as digits as its factorization.

643954424459257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5225472000, while the sum is 73.

The spelling of 643954424459257 in words is "six hundred forty-three trillion, nine hundred fifty-four billion, four hundred twenty-four million, four hundred fifty-nine thousand, two hundred fifty-seven".