6447768809 has 2 divisors, whose sum is σ = 6447768810. Its totient is φ = 6447768808.

The previous prime is 6447768757. The next prime is 6447768829. The reversal of 6447768809 is 9088677446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4080654400 + 2367114409 = 63880^2 + 48653^2 .

It is a cyclic number.

It is not a de Polignac number, because 6447768809 - 2²⁰ = 6446720233 is a prime.

It is a super-2 number, since 2×6447768809² = 83147445228626556962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6447768829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3223884404 + 3223884405.

It is an arithmetic number, because the mean of its divisors is an integer number (3223884405).

Almost surely, 2^6447768809 is an apocalyptic number.

It is an amenable number.

6447768809 is a deficient number, since it is larger than the sum of its proper divisors (1).

6447768809 is an equidigital number, since it uses as much as digits as its factorization.

6447768809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16257024, while the sum is 59.

The square root of 6447768809 is about 80298.0000311340. Note that the first 4 decimals coincide. The cubic root of 6447768809 is about 1861.2433211209.

The spelling of 6447768809 in words is "six billion, four hundred forty-seven million, seven hundred sixty-eight thousand, eight hundred nine".