138961109 has 6 divisors (see below), whose sum is σ = 161648694. Its totient is φ = 119109480.

The previous prime is 138961091. The next prime is 138961139. The reversal of 138961109 is 901169831.

It can be written as a sum of positive squares in only one way, i.e., 138133009 + 828100 = 11753^2 + 910^2 .

It is not a de Polignac number, because 138961109 - 2⁸ = 138960853 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 (138961139) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1417922 + ... + 1418019.

It is an arithmetic number, because the mean of its divisors is an integer number (26941449).

Almost surely, 2^138961109 is an apocalyptic number.

It is an amenable number.

138961109 is a deficient number, since it is larger than the sum of its proper divisors (22687585).

138961109 is an equidigital number, since it uses as much as digits as its factorization.

138961109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2835955 (or 2835948 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 138961109 is about 11788.1766613841. The cubic root of 138961109 is about 517.9618306426.

The spelling of 138961109 in words is "one hundred thirty-eight million, nine hundred sixty-one thousand, one hundred nine".