138640871 has 2 divisors, whose sum is σ = 138640872. Its totient is φ = 138640870.

The previous prime is 138640867. The next prime is 138640883. The reversal of 138640871 is 178046831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138640871 - 2² = 138640867 is a prime.

It is a super-2 number, since 2×138640871² = 38442582223277282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138640811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69320435 + 69320436.

It is an arithmetic number, because the mean of its divisors is an integer number (69320436).

Almost surely, 2^138640871 is an apocalyptic number.

138640871 is a deficient number, since it is larger than the sum of its proper divisors (1).

138640871 is an equidigital number, since it uses as much as digits as its factorization.

138640871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 138640871 is about 11774.5858101251. The cubic root of 138640871 is about 517.5636409554.

The spelling of 138640871 in words is "one hundred thirty-eight million, six hundred forty thousand, eight hundred seventy-one".