6400639943 has 2 divisors, whose sum is σ = 6400639944. Its totient is φ = 6400639942.

The previous prime is 6400639937. The next prime is 6400640017. The reversal of 6400639943 is 3499360046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6400639943 - 2¹⁸ = 6400377799 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6400639894 and 6400639903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6400639643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3200319971 + 3200319972.

It is an arithmetic number, because the mean of its divisors is an integer number (3200319972).

Almost surely, 2^6400639943 is an apocalyptic number.

6400639943 is a deficient number, since it is larger than the sum of its proper divisors (1).

6400639943 is an equidigital number, since it uses as much as digits as its factorization.

6400639943 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 44.

The square root of 6400639943 is about 80003.9995437728. Note that the first 3 decimals coincide. The cubic root of 6400639943 is about 1856.6974137219.

Adding to 6400639943 its reverse (3499360046), we get a palindrome (9899999989).

The spelling of 6400639943 in words is "six billion, four hundred million, six hundred thirty-nine thousand, nine hundred forty-three".