138919919 has 4 divisors (see below), whose sum is σ = 140218344. Its totient is φ = 137621496.

The previous prime is 138919901. The next prime is 138919933. The reversal of 138919919 is 919919831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 919919831 = 1427 ⋅644653.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138919919 is a prime.

It is a super-2 number, since 2×138919919² = 38597487789933122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138919619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 649052 + ... + 649265.

It is an arithmetic number, because the mean of its divisors is an integer number (35054586).

Almost surely, 2^138919919 is an apocalyptic number.

138919919 is a deficient number, since it is larger than the sum of its proper divisors (1298425).

138919919 is a wasteful number, since it uses less digits than its factorization.

138919919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1298424.

The product of its digits is 157464, while the sum is 50.

The square root of 138919919 is about 11786.4294423714. The cubic root of 138919919 is about 517.9106485618.

The spelling of 138919919 in words is "one hundred thirty-eight million, nine hundred nineteen thousand, nine hundred nineteen".