138171661 has 2 divisors, whose sum is σ = 138171662. Its totient is φ = 138171660.

The previous prime is 138171643. The next prime is 138171673. The reversal of 138171661 is 166171831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91795561 + 46376100 = 9581^2 + 6810^2 .

It is a cyclic number.

It is not a de Polignac number, because 138171661 - 2²⁵ = 104617229 is a prime.

It is a super-3 number, since 3×138171661³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138171641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69085830 + 69085831.

It is an arithmetic number, because the mean of its divisors is an integer number (69085831).

Almost surely, 2^138171661 is an apocalyptic number.

It is an amenable number.

138171661 is a deficient number, since it is larger than the sum of its proper divisors (1).

138171661 is an equidigital number, since it uses as much as digits as its factorization.

138171661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 34.

The square root of 138171661 is about 11754.6442311114. The cubic root of 138171661 is about 516.9791079107.

The spelling of 138171661 in words is "one hundred thirty-eight million, one hundred seventy-one thousand, six hundred sixty-one".