6447768805 has 4 divisors (see below), whose sum is σ = 7737322572. Its totient is φ = 5158215040.

The previous prime is 6447768757. The next prime is 6447768809. The reversal of 6447768805 is 5088677446.

It is a Cunningham number, because it is equal to 80298²+1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2321119684 + 4126649121 = 48178^2 + 64239^2 .

It is a de Polignac number, because none of the positive numbers 2^k-6447768805 is a prime.

It is a super-2 number, since 2×6447768805² = 83147445125462256050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6447768809) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 644776876 + ... + 644776885.

It is an arithmetic number, because the mean of its divisors is an integer number (1934330643).

Almost surely, 2^6447768805 is an apocalyptic number.

It is an amenable number.

6447768805 is a deficient number, since it is larger than the sum of its proper divisors (1289553767).

6447768805 is a wasteful number, since it uses less digits than its factorization.

6447768805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289553766.

The product of its (nonzero) digits is 9031680, while the sum is 55.

The square root of 6447768805 is about 80298.0000062268. Note that the first 5 decimals coincide. The cubic root of 6447768805 is about 1861.2433207360.

The spelling of 6447768805 in words is "six billion, four hundred forty-seven million, seven hundred sixty-eight thousand, eight hundred five".