66775057765 has 16 divisors (see below), whose sum is σ = 86804550000. Its totient is φ = 49310803776.

The previous prime is 66775057759. The next prime is 66775057777. The reversal of 66775057765 is 56775057766.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 53897801281 + 12877256484 = 232159^2 + 113478^2 .

It is not a de Polignac number, because 66775057765 - 2¹⁷ = 66774926693 is a prime.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 3028390 + ... + 3050359.

It is an arithmetic number, because the mean of its divisors is an integer number (5425284375).

Almost surely, 2^66775057765 is an apocalyptic number.

66775057765 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66775057765 is a deficient number, since it is larger than the sum of its proper divisors (20029492235).

66775057765 is an equidigital number, since it uses as much as digits as its factorization.

66775057765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6078793 (or 6078767 counting only the distinct ones).

The product of its (nonzero) digits is 64827000, while the sum is 61.

Subtracting from 66775057765 its reverse (56775057766), we obtain a palindrome (9999999999).

The spelling of 66775057765 in words is "sixty-six billion, seven hundred seventy-five million, fifty-seven thousand, seven hundred sixty-five".