138640637 has 2 divisors, whose sum is σ = 138640638. Its totient is φ = 138640636.

The previous prime is 138640613. The next prime is 138640657. The reversal of 138640637 is 736046831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 111746041 + 26894596 = 10571^2 + 5186^2 .

It is a cyclic number.

It is not a de Polignac number, because 138640637 - 2¹⁴ = 138624253 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138640637.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138640657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69320318 + 69320319.

It is an arithmetic number, because the mean of its divisors is an integer number (69320319).

Almost surely, 2^138640637 is an apocalyptic number.

It is an amenable number.

138640637 is a deficient number, since it is larger than the sum of its proper divisors (1).

138640637 is an equidigital number, since it uses as much as digits as its factorization.

138640637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 138640637 is about 11774.5758734657. The cubic root of 138640637 is about 517.5633497715.

The spelling of 138640637 in words is "one hundred thirty-eight million, six hundred forty thousand, six hundred thirty-seven".