66646841 has 4 divisors (see below), whose sum is σ = 66775284. Its totient is φ = 66518400.

The previous prime is 66646829. The next prime is 66646897. The reversal of 66646841 is 14864666.

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 31125241 + 35521600 = 5579^2 + 5960^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66646841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66646241) 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 3 ways as a sum of consecutive naturals, for example, 63440 + ... + 64481.

It is an arithmetic number, because the mean of its divisors is an integer number (16693821).

Almost surely, 2^66646841 is an apocalyptic number.

It is an amenable number.

66646841 is a deficient number, since it is larger than the sum of its proper divisors (128443).

66646841 is a wasteful number, since it uses less digits than its factorization.

66646841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128442.

The product of its digits is 165888, while the sum is 41.

The square root of 66646841 is about 8163.7516498237. The cubic root of 66646841 is about 405.4399344834.

The spelling of 66646841 in words is "sixty-six million, six hundred forty-six thousand, eight hundred forty-one".