138505813 has 4 divisors (see below), whose sum is σ = 138957280. Its totient is φ = 138054348.

The previous prime is 138505789. The next prime is 138505823. The reversal of 138505813 is 318505831.

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.

It is a cyclic number.

It is not a de Polignac number, because 138505813 - 2¹³ = 138497621 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 (138505823) 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, 225273 + ... + 225886.

It is an arithmetic number, because the mean of its divisors is an integer number (34739320).

Almost surely, 2^138505813 is an apocalyptic number.

It is an amenable number.

138505813 is a deficient number, since it is larger than the sum of its proper divisors (451467).

138505813 is an equidigital number, since it uses as much as digits as its factorization.

138505813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451466.

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 138505813 is about 11768.8492640530. The cubic root of 138505813 is about 517.3955235736.

The spelling of 138505813 in words is "one hundred thirty-eight million, five hundred five thousand, eight hundred thirteen".