138540861 has 24 divisors (see below), whose sum is σ = 210057120. Its totient is φ = 91234512.

The previous prime is 138540847. The next prime is 138540869. The reversal of 138540861 is 168045831.

138540861 is a `hidden beast` number, since 1 + 38 + 540 + 86 + 1 = 666.

It is not a de Polignac number, because 138540861 - 2²¹ = 136443709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138540869) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16735 + ... + 23603.

It is an arithmetic number, because the mean of its divisors is an integer number (8752380).

Almost surely, 2^138540861 is an apocalyptic number.

It is an amenable number.

138540861 is a deficient number, since it is larger than the sum of its proper divisors (71516259).

138540861 is an frugal number, since it uses more digits than its factorization.

138540861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6967 (or 6955 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 138540861 is about 11770.3381854558. The cubic root of 138540861 is about 517.4391610898.

The spelling of 138540861 in words is "one hundred thirty-eight million, five hundred forty thousand, eight hundred sixty-one".