6420978778 has 16 divisors (see below), whose sum is σ = 10262989224. Its totient is φ = 3002388480.

The previous prime is 6420978763. The next prime is 6420978857. The reversal of 6420978778 is 8778790246.

It can be written as a sum of positive squares in 4 ways, for example, as 6306424569 + 114554209 = 79413^2 + 10703^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 596103 + ... + 606778.

Almost surely, 2^6420978778 is an apocalyptic number.

6420978778 is a deficient number, since it is larger than the sum of its proper divisors (3842010446).

6420978778 is a wasteful number, since it uses less digits than its factorization.

6420978778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1203057.

The product of its (nonzero) digits is 9483264, while the sum is 58.

The square root of 6420978778 is about 80131.0100897274. The cubic root of 6420978778 is about 1858.6619638392.

The spelling of 6420978778 in words is "six billion, four hundred twenty million, nine hundred seventy-eight thousand, seven hundred seventy-eight".