66681005 has 16 divisors (see below), whose sum is σ = 83023920. Its totient is φ = 51351552.

The previous prime is 66680989. The next prime is 66681007. The reversal of 66681005 is 50018666.

It can be written as a sum of positive squares in 8 ways, for example, as 5262436 + 61418569 = 2294^2 + 7837^2 .

It is a cyclic number.

It is not a de Polignac number, because 66681005 - 2⁴ = 66680989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66681007) 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 15 ways as a sum of consecutive naturals, for example, 83267 + ... + 84063.

It is an arithmetic number, because the mean of its divisors is an integer number (5188995).

Almost surely, 2^66681005 is an apocalyptic number.

It is an amenable number.

66681005 is a deficient number, since it is larger than the sum of its proper divisors (16342915).

66681005 is a wasteful number, since it uses less digits than its factorization.

66681005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 66681005 is about 8165.8438020819. The cubic root of 66681005 is about 405.5092005010.

The spelling of 66681005 in words is "sixty-six million, six hundred eighty-one thousand, five".