138663681 has 16 divisors (see below), whose sum is σ = 203965440. Its totient is φ = 83249280.

The previous prime is 138663667. The next prime is 138663683. The reversal of 138663681 is 186366831.

It is not a de Polignac number, because 138663681 - 2⁵ = 138663649 is a prime.

It is a super-2 number, since 2×138663681² = 38455232856939522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (138663683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41761 + ... + 44958.

It is an arithmetic number, because the mean of its divisors is an integer number (12747840).

Almost surely, 2^138663681 is an apocalyptic number.

It is an amenable number.

138663681 is a deficient number, since it is larger than the sum of its proper divisors (65301759).

138663681 is a wasteful number, since it uses less digits than its factorization.

138663681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86776.

The product of its digits is 124416, while the sum is 42.

The square root of 138663681 is about 11775.5543818540. The cubic root of 138663681 is about 517.5920235893.

The spelling of 138663681 in words is "one hundred thirty-eight million, six hundred sixty-three thousand, six hundred eighty-one".