66781273 has 4 divisors (see below), whose sum is σ = 71918308. Its totient is φ = 61644240.

The previous prime is 66781261. The next prime is 66781277. The reversal of 66781273 is 37218766.

66781273 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32171584 + 34609689 = 5672^2 + 5883^2 .

It is a cyclic number.

It is not a de Polignac number, because 66781273 - 2⁵ = 66781241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66781277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2568498 + ... + 2568523.

It is an arithmetic number, because the mean of its divisors is an integer number (17979577).

Almost surely, 2^66781273 is an apocalyptic number.

It is an amenable number.

66781273 is a deficient number, since it is larger than the sum of its proper divisors (5137035).

66781273 is a wasteful number, since it uses less digits than its factorization.

66781273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5137034.

The product of its digits is 84672, while the sum is 40.

The square root of 66781273 is about 8171.9809715882. The cubic root of 66781273 is about 405.7123529761.

The spelling of 66781273 in words is "sixty-six million, seven hundred eighty-one thousand, two hundred seventy-three".