138680561 has 2 divisors, whose sum is σ = 138680562. Its totient is φ = 138680560.

The previous prime is 138680557. The next prime is 138680569. The reversal of 138680561 is 165086831.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 137334961 + 1345600 = 11719^2 + 1160^2 .

It is a cyclic number.

It is not a de Polignac number, because 138680561 - 2² = 138680557 is a prime.

It is not a weakly prime, because it can be changed into another prime (138680569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69340280 + 69340281.

It is an arithmetic number, because the mean of its divisors is an integer number (69340281).

Almost surely, 2^138680561 is an apocalyptic number.

It is an amenable number.

138680561 is a deficient number, since it is larger than the sum of its proper divisors (1).

138680561 is an equidigital number, since it uses as much as digits as its factorization.

138680561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 138680561 is about 11776.2710991213. The cubic root of 138680561 is about 517.6130254811.

The spelling of 138680561 in words is "one hundred thirty-eight million, six hundred eighty thousand, five hundred sixty-one".