138866891 has 2 divisors, whose sum is σ = 138866892. Its totient is φ = 138866890.

The previous prime is 138866879. The next prime is 138866929. The reversal of 138866891 is 198668831.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (198668831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138866891 - 2¹⁴ = 138850507 is a prime.

It is not a weakly prime, because it can be changed into another prime (138866191) 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 as a sum of consecutive naturals, namely, 69433445 + 69433446.

It is an arithmetic number, because the mean of its divisors is an integer number (69433446).

Almost surely, 2^138866891 is an apocalyptic number.

138866891 is a deficient number, since it is larger than the sum of its proper divisors (1).

138866891 is an equidigital number, since it uses as much as digits as its factorization.

138866891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 497664, while the sum is 50.

The square root of 138866891 is about 11784.1796914338. The cubic root of 138866891 is about 517.8447418599.

The spelling of 138866891 in words is "one hundred thirty-eight million, eight hundred sixty-six thousand, eight hundred ninety-one".