138666287 has 4 divisors (see below), whose sum is σ = 144695280. Its totient is φ = 132637296.

The previous prime is 138666277. The next prime is 138666289. The reversal of 138666287 is 782666831.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138666287 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138666289) 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 3 ways as a sum of consecutive naturals, for example, 3014462 + ... + 3014507.

It is an arithmetic number, because the mean of its divisors is an integer number (36173820).

Almost surely, 2^138666287 is an apocalyptic number.

138666287 is a deficient number, since it is larger than the sum of its proper divisors (6028993).

138666287 is an equidigital number, since it uses as much as digits as its factorization.

138666287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6028992.

The product of its digits is 580608, while the sum is 47.

The square root of 138666287 is about 11775.6650342985. The cubic root of 138666287 is about 517.5952660543.

The spelling of 138666287 in words is "one hundred thirty-eight million, six hundred sixty-six thousand, two hundred eighty-seven".