138123217 has 4 divisors (see below), whose sum is σ = 145392880. Its totient is φ = 130853556.

The previous prime is 138123203. The next prime is 138123229. The reversal of 138123217 is 712321831.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 712321831 = 13 ⋅54793987.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138123217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138123277) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3634803 + ... + 3634840.

It is an arithmetic number, because the mean of its divisors is an integer number (36348220).

Almost surely, 2^138123217 is an apocalyptic number.

It is an amenable number.

138123217 is a deficient number, since it is larger than the sum of its proper divisors (7269663).

138123217 is an equidigital number, since it uses as much as digits as its factorization.

138123217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7269662.

The product of its digits is 2016, while the sum is 28.

The square root of 138123217 is about 11752.5834181256. The cubic root of 138123217 is about 516.9186819564.

The spelling of 138123217 in words is "one hundred thirty-eight million, one hundred twenty-three thousand, two hundred seventeen".