6766387721 has 2 divisors, whose sum is σ = 6766387722. Its totient is φ = 6766387720.

The previous prime is 6766387717. The next prime is 6766387799. The reversal of 6766387721 is 1277836676.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5626650121 + 1139737600 = 75011^2 + 33760^2 .

It is a cyclic number.

It is not a de Polignac number, because 6766387721 - 2² = 6766387717 is a prime.

It is not a weakly prime, because it can be changed into another prime (6763387721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3383193860 + 3383193861.

It is an arithmetic number, because the mean of its divisors is an integer number (3383193861).

Almost surely, 2^6766387721 is an apocalyptic number.

It is an amenable number.

6766387721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6766387721 is an equidigital number, since it uses as much as digits as its factorization.

6766387721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3556224, while the sum is 53.

The square root of 6766387721 is about 82258.0556602209. The cubic root of 6766387721 is about 1891.4097635799.

The spelling of 6766387721 in words is "six billion, seven hundred sixty-six million, three hundred eighty-seven thousand, seven hundred twenty-one".