6391778065 has 8 divisors (see below), whose sum is σ = 8121318120. Its totient is φ = 4812632832.

The previous prime is 6391778033. The next prime is 6391778093. The reversal of 6391778065 is 5608771936.

It can be written as a sum of positive squares in 4 ways, for example, as 105349696 + 6286428369 = 10264^2 + 79287^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6391778065 - 2⁵ = 6391778033 is a prime.

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, 37598610 + ... + 37598779.

It is an arithmetic number, because the mean of its divisors is an integer number (1015164765).

Almost surely, 2^6391778065 is an apocalyptic number.

It is an amenable number.

6391778065 is a deficient number, since it is larger than the sum of its proper divisors (1729540055).

6391778065 is a wasteful number, since it uses less digits than its factorization.

6391778065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75197411.

The product of its (nonzero) digits is 1905120, while the sum is 52.

The square root of 6391778065 is about 79948.5963916816. The cubic root of 6391778065 is about 1855.8401335353.

The spelling of 6391778065 in words is "six billion, three hundred ninety-one million, seven hundred seventy-eight thousand, sixty-five".