643486849 has 2 divisors, whose sum is σ = 643486850. Its totient is φ = 643486848.

The previous prime is 643486817. The next prime is 643486867. The reversal of 643486849 is 948684346.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 393625600 + 249861249 = 19840^2 + 15807^2 .

It is a cyclic number.

It is not a de Polignac number, because 643486849 - 2⁵ = 643486817 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643486796 and 643486805.

It is not a weakly prime, because it can be changed into another prime (643487849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321743424 + 321743425.

It is an arithmetic number, because the mean of its divisors is an integer number (321743425).

Almost surely, 2^643486849 is an apocalyptic number.

It is an amenable number.

643486849 is a deficient number, since it is larger than the sum of its proper divisors (1).

643486849 is an equidigital number, since it uses as much as digits as its factorization.

643486849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3981312, while the sum is 52.

The square root of 643486849 is about 25367.0425749633. The cubic root of 643486849 is about 863.3360816272.

The spelling of 643486849 in words is "six hundred forty-three million, four hundred eighty-six thousand, eight hundred forty-nine".