6691477789 has 2 divisors, whose sum is σ = 6691477790. Its totient is φ = 6691477788.

The previous prime is 6691477781. The next prime is 6691477841. The reversal of 6691477789 is 9877741966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6676524100 + 14953689 = 81710^2 + 3867^2 .

It is a cyclic number.

It is not a de Polignac number, because 6691477789 - 2³ = 6691477781 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6691477789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6691477781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3345738894 + 3345738895.

It is an arithmetic number, because the mean of its divisors is an integer number (3345738895).

Almost surely, 2^6691477789 is an apocalyptic number.

It is an amenable number.

6691477789 is a deficient number, since it is larger than the sum of its proper divisors (1).

6691477789 is an equidigital number, since it uses as much as digits as its factorization.

6691477789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32006016, while the sum is 64.

The square root of 6691477789 is about 81801.4534650821. The cubic root of 6691477789 is about 1884.4039832690.

The spelling of 6691477789 in words is "six billion, six hundred ninety-one million, four hundred seventy-seven thousand, seven hundred eighty-nine".