138640669 has 2 divisors, whose sum is σ = 138640670. Its totient is φ = 138640668.

The previous prime is 138640657. The next prime is 138640681. The reversal of 138640669 is 966046831.

138640669 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (138640657) and next prime (138640681).

It can be written as a sum of positive squares in only one way, i.e., 109620900 + 29019769 = 10470^2 + 5387^2 .

It is a cyclic number.

It is not a de Polignac number, because 138640669 - 2⁵ = 138640637 is a prime.

It is a super-2 number, since 2×138640669² = 38442470201535122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138640699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69320334 + 69320335.

It is an arithmetic number, because the mean of its divisors is an integer number (69320335).

Almost surely, 2^138640669 is an apocalyptic number.

It is an amenable number.

138640669 is a deficient number, since it is larger than the sum of its proper divisors (1).

138640669 is an equidigital number, since it uses as much as digits as its factorization.

138640669 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 138640669 is about 11774.5772323256. The cubic root of 138640669 is about 517.5633895916.

The spelling of 138640669 in words is "one hundred thirty-eight million, six hundred forty thousand, six hundred sixty-nine".