138679804985121 has 21 divisors (see below), whose sum is σ = 207925067734051. Its totient is φ = 92452991351112.

The previous prime is 138679804985047. The next prime is 138679804985129. The reversal of 138679804985121 is 121589408976831.

It is a happy number.

The square root of 138679804985121 is 11776239.

It is a perfect power (a square), and thus also a powerful number.

138679804985121 is a `hidden beast` number, since 1 + 3 + 8 + 6 + 7 + 9 + 8 + 0 + 498 + 5 + 121 = 666.

It can be written as a sum of positive squares in only one way, i.e., 41629013723025 + 97050791262096 = 6452055^2 + 9851436^2 .

It is a de Polignac number, because none of the positive numbers 2^k-138679804985121 is a prime.

It is a super-2 number, since 2×138679804985121² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138679804985121.

It is not an unprimeable number, because it can be changed into a prime (138679804985129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 317740375 + ... + 318176531.

It is a 1-persistent number, because it is pandigital, but 2⋅138679804985121 = 277359609970242 is not.

Almost surely, 2^{138679804985121} is an apocalyptic number.

138679804985121 is the 11776239-th square number.

138679804985121 is the 5888120-th centered octagonal number.

It is an amenable number.

138679804985121 is a deficient number, since it is larger than the sum of its proper divisors (69245262748930).

138679804985121 is an frugal number, since it uses more digits than its factorization.

138679804985121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 872332 (or 436160 counting only the distinct ones).

The product of its (nonzero) digits is 209018880, while the sum is 72.

The spelling of 138679804985121 in words is "one hundred thirty-eight trillion, six hundred seventy-nine billion, eight hundred four million, nine hundred eighty-five thousand, one hundred twenty-one".