138218791 has 8 divisors (see below), whose sum is σ = 142102064. Its totient is φ = 134343360.

The previous prime is 138218779. The next prime is 138218797. The reversal of 138218791 is 197812831.

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 138218791 - 2¹³ = 138210599 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138218797) 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, 63796 + ... + 65926.

It is an arithmetic number, because the mean of its divisors is an integer number (17762758).

Almost surely, 2^138218791 is an apocalyptic number.

138218791 is a deficient number, since it is larger than the sum of its proper divisors (3883273).

138218791 is a wasteful number, since it uses less digits than its factorization.

138218791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3921.

The product of its digits is 24192, while the sum is 40.

The square root of 138218791 is about 11756.6487997218. The cubic root of 138218791 is about 517.0378813123.

The spelling of 138218791 in words is "one hundred thirty-eight million, two hundred eighteen thousand, seven hundred ninety-one".