138546921581 has 2 divisors, whose sum is σ = 138546921582. Its totient is φ = 138546921580.

The previous prime is 138546921511. The next prime is 138546921593. The reversal of 138546921581 is 185129645831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 137885968900 + 660952681 = 371330^2 + 25709^2 .

It is a cyclic number.

It is not a de Polignac number, because 138546921581 - 2³⁰ = 137473179757 is a prime.

It is a super-2 number, since 2×138546921581² (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 (138546921511) 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 as a sum of consecutive naturals, namely, 69273460790 + 69273460791.

It is an arithmetic number, because the mean of its divisors is an integer number (69273460791).

Almost surely, 2^138546921581 is an apocalyptic number.

It is an amenable number.

138546921581 is a deficient number, since it is larger than the sum of its proper divisors (1).

138546921581 is an equidigital number, since it uses as much as digits as its factorization.

138546921581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2073600, while the sum is 53.

The spelling of 138546921581 in words is "one hundred thirty-eight billion, five hundred forty-six million, nine hundred twenty-one thousand, five hundred eighty-one".