6643878869 has 2 divisors, whose sum is σ = 6643878870. Its totient is φ = 6643878868.

The previous prime is 6643878811. The next prime is 6643878893. The reversal of 6643878869 is 9688783466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6035269969 + 608608900 = 77687^2 + 24670^2 .

It is a cyclic number.

It is not a de Polignac number, because 6643878869 - 2²⁸ = 6375443413 is a prime.

It is a super-2 number, since 2×6643878869² = 88282252851889438322, which contains 22 as substring.

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 (6643878809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3321939434 + 3321939435.

It is an arithmetic number, because the mean of its divisors is an integer number (3321939435).

Almost surely, 2^6643878869 is an apocalyptic number.

It is an amenable number.

6643878869 is a deficient number, since it is larger than the sum of its proper divisors (1).

6643878869 is an equidigital number, since it uses as much as digits as its factorization.

6643878869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 83607552, while the sum is 65.

The square root of 6643878869 is about 81509.9924487789. The cubic root of 6643878869 is about 1879.9251959258.

The spelling of 6643878869 in words is "six billion, six hundred forty-three million, eight hundred seventy-eight thousand, eight hundred sixty-nine".