138643939 has 8 divisors (see below), whose sum is σ = 158732288. Its totient is φ = 118626120.

The previous prime is 138643907. The next prime is 138643949. The reversal of 138643939 is 939346831.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 138643939 - 2⁵ = 138643907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138643949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13347 + ... + 21340.

It is an arithmetic number, because the mean of its divisors is an integer number (19841536).

Almost surely, 2^138643939 is an apocalyptic number.

138643939 is a deficient number, since it is larger than the sum of its proper divisors (20088349).

138643939 is an equidigital number, since it uses as much as digits as its factorization.

138643939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35265.

The product of its digits is 419904, while the sum is 46.

The square root of 138643939 is about 11774.7160899955. The cubic root of 138643939 is about 517.5674586693.

The spelling of 138643939 in words is "one hundred thirty-eight million, six hundred forty-three thousand, nine hundred thirty-nine".