138661 has 2 divisors, whose sum is σ = 138662. Its totient is φ = 138660.
The previous prime is 138647. The next prime is 138679. The reversal of 138661 is 166831.
138661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 136161 + 2500 = 369^2 + 50^2 .
It is a cyclic number.
It is not a de Polignac number, because 138661 - 25 = 138629 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (138641) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69330 + 69331.
It is an arithmetic number, because the mean of its divisors is an integer number (69331).
2138661 is an apocalyptic number.
It is an amenable number.
138661 is a deficient number, since it is larger than the sum of its proper divisors (1).
138661 is an equidigital number, since it uses as much as digits as its factorization.
138661 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 864, while the sum is 25.
The square root of 138661 is about 372.3721257022. The cubic root of 138661 is about 51.7588687765.
The spelling of 138661 in words is "one hundred thirty-eight thousand, six hundred sixty-one".
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