138321681 has 8 divisors (see below), whose sum is σ = 184511904. Its totient is φ = 92172960.

The previous prime is 138321671. The next prime is 138321719. The reversal of 138321681 is 186123831.

138321681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138321681 - 2⁵ = 138321649 is a prime.

It is a super-2 number, since 2×138321681² = 38265774869331522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (138321671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1516 + ... + 16701.

It is an arithmetic number, because the mean of its divisors is an integer number (23063988).

Almost surely, 2^138321681 is an apocalyptic number.

It is an amenable number.

138321681 is a deficient number, since it is larger than the sum of its proper divisors (46190223).

138321681 is a wasteful number, since it uses less digits than its factorization.

138321681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20751.

The product of its digits is 6912, while the sum is 33.

The square root of 138321681 is about 11761.0238074753. The cubic root of 138321681 is about 517.1661437396.

The spelling of 138321681 in words is "one hundred thirty-eight million, three hundred twenty-one thousand, six hundred eighty-one".