66566281 has 4 divisors (see below), whose sum is σ = 68861700. Its totient is φ = 64270864.

The previous prime is 66566267. The next prime is 66566287. The reversal of 66566281 is 18266566.

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 46172025 + 20394256 = 6795^2 + 4516^2 .

It is a cyclic number.

It is not a de Polignac number, because 66566281 - 2⁹ = 66565769 is a prime.

It is a super-2 number, since 2×66566281² = 8862139532341922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66566287) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1147666 + ... + 1147723.

It is an arithmetic number, because the mean of its divisors is an integer number (17215425).

Almost surely, 2^66566281 is an apocalyptic number.

It is an amenable number.

66566281 is a deficient number, since it is larger than the sum of its proper divisors (2295419).

66566281 is a wasteful number, since it uses less digits than its factorization.

66566281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2295418.

The product of its digits is 103680, while the sum is 40.

The square root of 66566281 is about 8158.8161518691. The cubic root of 66566281 is about 405.2765088319.

The spelling of 66566281 in words is "sixty-six million, five hundred sixty-six thousand, two hundred eighty-one".