6440778993 has 16 divisors (see below), whose sum is σ = 9391787712. Its totient is φ = 3893760000.

The previous prime is 6440778947. The next prime is 6440779019. The reversal of 6440778993 is 3998770446.

It is not a de Polignac number, because 6440778993 - 2¹⁶ = 6440713457 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6440778893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 230128 + ... + 256593.

It is an arithmetic number, because the mean of its divisors is an integer number (586986732).

Almost surely, 2^6440778993 is an apocalyptic number.

It is an amenable number.

6440778993 is a deficient number, since it is larger than the sum of its proper divisors (2951008719).

6440778993 is a wasteful number, since it uses less digits than its factorization.

6440778993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487136.

The product of its (nonzero) digits is 9144576, while the sum is 57.

The square root of 6440778993 is about 80254.4640066831. The cubic root of 6440778993 is about 1860.5705068646.

The spelling of 6440778993 in words is "six billion, four hundred forty million, seven hundred seventy-eight thousand, nine hundred ninety-three".