6440778947 has 2 divisors, whose sum is σ = 6440778948. Its totient is φ = 6440778946.

The previous prime is 6440778931. The next prime is 6440779019. The reversal of 6440778947 is 7498770446.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6440778947 - 2⁴ = 6440778931 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6440778892 and 6440778901.

It is not a weakly prime, because it can be changed into another prime (6440778907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3220389473 + 3220389474.

It is an arithmetic number, because the mean of its divisors is an integer number (3220389474).

Almost surely, 2^6440778947 is an apocalyptic number.

6440778947 is a deficient number, since it is larger than the sum of its proper divisors (1).

6440778947 is an equidigital number, since it uses as much as digits as its factorization.

6440778947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9483264, while the sum is 56.

The square root of 6440778947 is about 80254.4637200947. The cubic root of 6440778947 is about 1860.5705024352.

The spelling of 6440778947 in words is "six billion, four hundred forty million, seven hundred seventy-eight thousand, nine hundred forty-seven".