66394881 has 24 divisors (see below), whose sum is σ = 112157760. Its totient is φ = 37056096.

The previous prime is 66394871. The next prime is 66394907. The reversal of 66394881 is 18849366.

66394881 is a `hidden beast` number, since 6 + 639 + 4 + 8 + 8 + 1 = 666.

66394881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66394881 - 2⁶ = 66394817 is a prime.

It is a super-2 number, since 2×66394881² = 8816560446008322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66394831) 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 23 ways as a sum of consecutive naturals, for example, 9546 + ... + 14963.

It is an arithmetic number, because the mean of its divisors is an integer number (4673240).

Almost surely, 2^66394881 is an apocalyptic number.

It is an amenable number.

66394881 is a deficient number, since it is larger than the sum of its proper divisors (45762879).

66394881 is a wasteful number, since it uses less digits than its factorization.

66394881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24565 (or 24562 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 66394881 is about 8148.3054066474. The cubic root of 66394881 is about 404.9283641017.

The spelling of 66394881 in words is "sixty-six million, three hundred ninety-four thousand, eight hundred eighty-one".