138198437 has 4 divisors (see below), whose sum is σ = 148829100. Its totient is φ = 127567776.

The previous prime is 138198397. The next prime is 138198443. The reversal of 138198437 is 734891831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 734891831 = 41 ⋅17924191.

It can be written as a sum of positive squares in 2 ways, for example, as 10982596 + 127215841 = 3314^2 + 11279^2 .

It is a cyclic number.

It is not a de Polignac number, because 138198437 - 2⁶ = 138198373 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 (138108437) 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, 5315312 + ... + 5315337.

It is an arithmetic number, because the mean of its divisors is an integer number (37207275).

Almost surely, 2^138198437 is an apocalyptic number.

It is an amenable number.

138198437 is a deficient number, since it is larger than the sum of its proper divisors (10630663).

138198437 is a wasteful number, since it uses less digits than its factorization.

138198437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10630662.

The product of its digits is 145152, while the sum is 44.

The square root of 138198437 is about 11755.7831300173. The cubic root of 138198437 is about 517.0125005239.

The spelling of 138198437 in words is "one hundred thirty-eight million, one hundred ninety-eight thousand, four hundred thirty-seven".