138640667 has 4 divisors (see below), whose sum is σ = 151244376. Its totient is φ = 126036960.

The previous prime is 138640657. The next prime is 138640669. The reversal of 138640667 is 766046831.

138640667 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 766046831 = 11 ⋅69640621.

It is a cyclic number.

It is not a de Polignac number, because 138640667 - 2¹⁰ = 138639643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138640669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6301838 + ... + 6301859.

It is an arithmetic number, because the mean of its divisors is an integer number (37811094).

Almost surely, 2^138640667 is an apocalyptic number.

138640667 is a deficient number, since it is larger than the sum of its proper divisors (12603709).

138640667 is a wasteful number, since it uses less digits than its factorization.

138640667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12603708.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 138640667 is about 11774.5771473968. The cubic root of 138640667 is about 517.5633871028.

The spelling of 138640667 in words is "one hundred thirty-eight million, six hundred forty thousand, six hundred sixty-seven".