138959861 has 4 divisors (see below), whose sum is σ = 138988800. Its totient is φ = 138930924.

The previous prime is 138959837. The next prime is 138959867. The reversal of 138959861 is 168959831.

It is a happy number.

138959861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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: 168959831 = 2371 ⋅71261.

It is a cyclic number.

It is not a de Polignac number, because 138959861 - 2¹⁸ = 138697717 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 (138959867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5351 + ... + 17508.

It is an arithmetic number, because the mean of its divisors is an integer number (34747200).

Almost surely, 2^138959861 is an apocalyptic number.

It is an amenable number.

138959861 is a deficient number, since it is larger than the sum of its proper divisors (28939).

138959861 is an equidigital number, since it uses as much as digits as its factorization.

138959861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28938.

The product of its digits is 466560, while the sum is 50.

The square root of 138959861 is about 11788.1237268702. The cubic root of 138959861 is about 517.9602800450.

The spelling of 138959861 in words is "one hundred thirty-eight million, nine hundred fifty-nine thousand, eight hundred sixty-one".