138235661 has 2 divisors, whose sum is σ = 138235662. Its totient is φ = 138235660.

The previous prime is 138235633. The next prime is 138235667. The reversal of 138235661 is 166532831.

138235661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 119486761 + 18748900 = 10931^2 + 4330^2 .

It is an emirp because it is prime and its reverse (166532831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138235661 - 2²² = 134041357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138235667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69117830 + 69117831.

It is an arithmetic number, because the mean of its divisors is an integer number (69117831).

Almost surely, 2^138235661 is an apocalyptic number.

It is an amenable number.

138235661 is a deficient number, since it is larger than the sum of its proper divisors (1).

138235661 is an equidigital number, since it uses as much as digits as its factorization.

138235661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 138235661 is about 11757.3662441892. The cubic root of 138235661 is about 517.0589157755.

The spelling of 138235661 in words is "one hundred thirty-eight million, two hundred thirty-five thousand, six hundred sixty-one".