138116021 has 4 divisors (see below), whose sum is σ = 138174912. Its totient is φ = 138057132.

The previous prime is 138115987. The next prime is 138116023. The reversal of 138116021 is 120611831.

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: 120611831 = 131 ⋅920701.

It is a cyclic number.

It is not a de Polignac number, because 138116021 - 2²² = 133921717 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 (138116023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25775 + ... + 30668.

It is an arithmetic number, because the mean of its divisors is an integer number (34543728).

Almost surely, 2^138116021 is an apocalyptic number.

It is an amenable number.

138116021 is a deficient number, since it is larger than the sum of its proper divisors (58891).

138116021 is an equidigital number, since it uses as much as digits as its factorization.

138116021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58890.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 138116021 is about 11752.2772686829. The cubic root of 138116021 is about 516.9097049200.

Adding to 138116021 its reverse (120611831), we get a palindrome (258727852).

The spelling of 138116021 in words is "one hundred thirty-eight million, one hundred sixteen thousand, twenty-one".