138891666601 has 2 divisors, whose sum is σ = 138891666602. Its totient is φ = 138891666600.

The previous prime is 138891666533. The next prime is 138891666611. The reversal of 138891666601 is 106666198831.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138625160976 + 266505625 = 372324^2 + 16325^2 .

It is an emirp because it is prime and its reverse (106666198831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138891666601 - 2²⁷ = 138757448873 is a prime.

It is not a weakly prime, because it can be changed into another prime (138891666611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69445833300 + 69445833301.

It is an arithmetic number, because the mean of its divisors is an integer number (69445833301).

Almost surely, 2^138891666601 is an apocalyptic number.

It is an amenable number.

138891666601 is a deficient number, since it is larger than the sum of its proper divisors (1).

138891666601 is an equidigital number, since it uses as much as digits as its factorization.

138891666601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2239488, while the sum is 55.

The spelling of 138891666601 in words is "one hundred thirty-eight billion, eight hundred ninety-one million, six hundred sixty-six thousand, six hundred one".