138188194981 has 2 divisors, whose sum is σ = 138188194982. Its totient is φ = 138188194980.

The previous prime is 138188194957. The next prime is 138188195027. The reversal of 138188194981 is 189491881831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70884270081 + 67303924900 = 266241^2 + 259430^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138188194981 is a prime.

It is a super-2 number, since 2×138188194981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138188194181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69094097490 + 69094097491.

It is an arithmetic number, because the mean of its divisors is an integer number (69094097491).

Almost surely, 2^138188194981 is an apocalyptic number.

It is an amenable number.

138188194981 is a deficient number, since it is larger than the sum of its proper divisors (1).

138188194981 is an equidigital number, since it uses as much as digits as its factorization.

138188194981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3981312, while the sum is 61.

The spelling of 138188194981 in words is "one hundred thirty-eight billion, one hundred eighty-eight million, one hundred ninety-four thousand, nine hundred eighty-one".