138606866 has 4 divisors (see below), whose sum is σ = 207910302. Its totient is φ = 69303432.

The previous prime is 138606821. The next prime is 138606869. The reversal of 138606866 is 668606831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 668606831 = 257 ⋅2601583.

It can be written as a sum of positive squares in only one way, i.e., 113316025 + 25290841 = 10645^2 + 5029^2 .

It is not an unprimeable number, because it can be changed into a prime (138606869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34651715 + ... + 34651718.

Almost surely, 2^138606866 is an apocalyptic number.

138606866 is a deficient number, since it is larger than the sum of its proper divisors (69303436).

138606866 is an equidigital number, since it uses as much as digits as its factorization.

138606866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69303435.

The product of its (nonzero) digits is 248832, while the sum is 44.

The square root of 138606866 is about 11773.1417217326. The cubic root of 138606866 is about 517.5213225284.

The spelling of 138606866 in words is "one hundred thirty-eight million, six hundred six thousand, eight hundred sixty-six".