66780181 has 12 divisors (see below), whose sum is σ = 73316388. Its totient is φ = 60787584.

The previous prime is 66780151. The next prime is 66780209. The reversal of 66780181 is 18108766.

It can be written as a sum of positive squares in 6 ways, for example, as 15729156 + 51051025 = 3966^2 + 7145^2 .

It is not a de Polignac number, because 66780181 - 2⁵ = 66780149 is a prime.

It is a super-2 number, since 2×66780181² = 8919185148785522, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 66780181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66780101) 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 in 11 ways as a sum of consecutive naturals, for example, 9631 + ... + 15043.

It is an arithmetic number, because the mean of its divisors is an integer number (6109699).

Almost surely, 2^66780181 is an apocalyptic number.

It is an amenable number.

66780181 is a deficient number, since it is larger than the sum of its proper divisors (6536207).

66780181 is a wasteful number, since it uses less digits than its factorization.

66780181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5512 (or 5499 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 66780181 is about 8171.9141576500. The cubic root of 66780181 is about 405.7101415762.

The spelling of 66780181 in words is "sixty-six million, seven hundred eighty thousand, one hundred eighty-one".