138638987 has 8 divisors (see below), whose sum is σ = 139860000. Its totient is φ = 137422144.

The previous prime is 138638959. The next prime is 138639001. The reversal of 138638987 is 789836831.

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 138638987 - 2¹⁰ = 138637963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138638957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131639 + ... + 132687.

It is an arithmetic number, because the mean of its divisors is an integer number (17482500).

Almost surely, 2^138638987 is an apocalyptic number.

138638987 is a deficient number, since it is larger than the sum of its proper divisors (1221013).

138638987 is a wasteful number, since it uses less digits than its factorization.

138638987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2085.

The product of its digits is 1741824, while the sum is 53.

The square root of 138638987 is about 11774.5058070392. The cubic root of 138638987 is about 517.5612965426.

The spelling of 138638987 in words is "one hundred thirty-eight million, six hundred thirty-eight thousand, nine hundred eighty-seven".