6699999781 has 2 divisors, whose sum is σ = 6699999782. Its totient is φ = 6699999780.

The previous prime is 6699999769. The next prime is 6699999793. The reversal of 6699999781 is 1879999966.

It is a balanced prime because it is at equal distance from previous prime (6699999769) and next prime (6699999793).

It can be written as a sum of positive squares in only one way, i.e., 4190490756 + 2509509025 = 64734^2 + 50095^2 .

It is a cyclic number.

It is not a de Polignac number, because 6699999781 - 2⁵ = 6699999749 is a prime.

It is a super-2 number, since 2×6699999781² = 89779994130800095922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6699999881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3349999890 + 3349999891.

It is an arithmetic number, because the mean of its divisors is an integer number (3349999891).

Almost surely, 2^6699999781 is an apocalyptic number.

It is an amenable number.

6699999781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6699999781 is an equidigital number, since it uses as much as digits as its factorization.

6699999781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 119042784, while the sum is 73.

The square root of 6699999781 is about 81853.5263809691. The cubic root of 6699999781 is about 1885.2036104807.

The spelling of 6699999781 in words is "six billion, six hundred ninety-nine million, nine hundred ninety-nine thousand, seven hundred eighty-one".