138555681 has 16 divisors (see below), whose sum is σ = 202657728. Its totient is φ = 83505600.

The previous prime is 138555667. The next prime is 138555689. The reversal of 138555681 is 186555831.

It is not a de Polignac number, because 138555681 - 2⁷ = 138555553 is a prime.

It is a super-2 number, since 2×138555681² = 38395353474747522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (138555689) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5626 + ... + 17571.

It is an arithmetic number, because the mean of its divisors is an integer number (12666108).

Almost surely, 2^138555681 is an apocalyptic number.

138555681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

138555681 is a deficient number, since it is larger than the sum of its proper divisors (64102047).

138555681 is a wasteful number, since it uses less digits than its factorization.

138555681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23392.

The product of its digits is 144000, while the sum is 42.

The square root of 138555681 is about 11770.9677172270. The cubic root of 138555681 is about 517.4576109414.

The spelling of 138555681 in words is "one hundred thirty-eight million, five hundred fifty-five thousand, six hundred eighty-one".