643845726481 has 2 divisors, whose sum is σ = 643845726482. Its totient is φ = 643845726480.

The previous prime is 643845726427. The next prime is 643845726541. The reversal of 643845726481 is 184627548346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 483998490000 + 159847236481 = 695700^2 + 399809^2 .

It is a cyclic number.

It is not a de Polignac number, because 643845726481 - 2²⁵ = 643812172049 is a prime.

It is a super-2 number, since 2×643845726481² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643845706481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321922863240 + 321922863241.

It is an arithmetic number, because the mean of its divisors is an integer number (321922863241).

Almost surely, 2^643845726481 is an apocalyptic number.

It is an amenable number.

643845726481 is a deficient number, since it is larger than the sum of its proper divisors (1).

643845726481 is an equidigital number, since it uses as much as digits as its factorization.

643845726481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30965760, while the sum is 58.

The spelling of 643845726481 in words is "six hundred forty-three billion, eight hundred forty-five million, seven hundred twenty-six thousand, four hundred eighty-one".