66397281 has 8 divisors (see below), whose sum is σ = 88883424. Its totient is φ = 44088000.

The previous prime is 66397271. The next prime is 66397301. The reversal of 66397281 is 18279366.

It is a happy number.

66397281 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66397281 - 2⁵ = 66397249 is a prime.

It is a super-2 number, since 2×66397281² = 8817197848385922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (66397271) 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 7 ways as a sum of consecutive naturals, for example, 43336 + ... + 44841.

It is an arithmetic number, because the mean of its divisors is an integer number (11110428).

Almost surely, 2^66397281 is an apocalyptic number.

It is an amenable number.

66397281 is a deficient number, since it is larger than the sum of its proper divisors (22486143).

66397281 is a wasteful number, since it uses less digits than its factorization.

66397281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88431.

The product of its digits is 108864, while the sum is 42.

The square root of 66397281 is about 8148.4526752016. The cubic root of 66397281 is about 404.9332430741.

The spelling of 66397281 in words is "sixty-six million, three hundred ninety-seven thousand, two hundred eighty-one".