138887861 has 4 divisors (see below), whose sum is σ = 158728992. Its totient is φ = 119046732.

The previous prime is 138887849. The next prime is 138887863. The reversal of 138887861 is 168788831.

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: 168788831 = 31 ⋅5444801.

It is not a de Polignac number, because 138887861 - 2²² = 134693557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138887863) 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, 9920555 + ... + 9920568.

It is an arithmetic number, because the mean of its divisors is an integer number (39682248).

Almost surely, 2^138887861 is an apocalyptic number.

It is an amenable number.

138887861 is a deficient number, since it is larger than the sum of its proper divisors (19841131).

138887861 is an equidigital number, since it uses as much as digits as its factorization.

138887861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19841130.

The product of its digits is 516096, while the sum is 50.

The square root of 138887861 is about 11785.0694100629. The cubic root of 138887861 is about 517.8708067666.

The spelling of 138887861 in words is "one hundred thirty-eight million, eight hundred eighty-seven thousand, eight hundred sixty-one".